I apologyze for the wall of text and if there are inconsistencies (English is not my first languaje so i used Google translate).
If you buy things and no taxes are paid, that's kind of illegal. ← If you live in a socialist (or pseudo-socialist) country, that doesn't matter anymore. Furthermore, it's not illegal per se; it does take advantage of a legal loophole, since it's not explicitly stated that this maneuver cannot be done. But hey, the advantage of living in a third-world country is that nobody cares.
'If you buy a Steam gift card with bitcoin, the cost of the on-chain transfer, just due to the power requirement, is higher than the value of the card.' ← If you buy anything with any payment method, you have an added cost (taxes, commissions, fees, etc.). Even for physical goods, if you buy an apple at a fruit shop, you're also paying (part of) the cost of the fuel, taxes, comissions, etc. used in shipping.
'Someone has to pay that cost.' ’ ← In everything (even for things unrelated to Bitcoin), the one who pays is the final consumer. I don't know what it's called in your country; in mine, we call it a 'transfer of value.' (For this reason, tax policies on the rich never work and end up making the cost of any product or service more expensive.)
‘Any "news" article you read about the supposed acceptance of Bitcoin is funded by people trying to fuel the bubble. ’ ← I wasn't referring to newspaper articles, but to videos you can find here and there. Also, evidence of that? (Don't make me defend the press, XD)
‘When Steam discontinued Bitcoin, a transfer did cost about the ’ <- Based on your cost argument. Yes, back then, transactions became expensive since there weren't a large number of nodes (called miners) processing transactions, so the network became saturated and the transaction fee skyrocketed.
But starting in 2018, the Lighting Network was implemented, allowing transfers (of small amounts) to be made instantly and commission-free (no network fees). It's what I use today to buy Steam Gift cards, or pay my VPN.
'If people use coins, does it become useless' Uh, no, money exists precisely to be exchanged for goods and services, not through barter. If by "coins" you mean cryptocurrencies, uh, no, either. Cryptocurrencies (e.g., Bitcoin) are a currency, period. They have their own characteristics (pros and cons), but they are a currency nonetheless. Made to be exchanged for things, or to save in. Yes, there are people who use it as an investment, buying now, waiting for the price to go up, and then selling it. But that's not the purpose of cryptocurrencies. For example, in Latin America, people do the same with the US dollar; it's bought and sold as an "investment," rather than used as a currency.
Based on the disadvantages of blockchains: do they get bogged down if too many people use them? If so, the entire network would have collapsed by now (Bitcoin emerged in 2009 and had its first boom in February 2017 (based on price)). And at most, there was an increase in network fees. But that has already been fixed with the increase in nodes (miners) globally and the Lighting Network.
'And if very few people use them, the system can be easily hacked.' Huh? How? The only possible way to hack the system is by capitalizing on the largest amount of the network's computing power (the so-called 51% attack, which in turn is so expensive as to be unfeasible, plus it would motivate people to use another protocol (currency), rendering the attack useless). Plus, Bitcoin already has several "safeguards" by desing specifically to prevent hacking: "proof of work," asymmetric cryptography, decentralized consensus, etc.
Plus, if that were the case, it would have been hacked as soon as it was made public.
'And the irony of all this is that the way people would use it to evade certain payment processors isn't even as a currency. It would be used like PayPal, with extra steps.' <- PayPal is using a currency with extra steps. You deposit a balance, make the transfer, and the recipient withdraws the money.(When possible, because there are also cases where PayPal or other payment or banking entities deny withdrawals, even if they are from legitimate sources.)
I save in Bitcoin and I also make my payments directly on the network (or through LN) without resorting to an exchange. It's true that in any case, most people would use exchanges as payment processors, but at least the opportunity to leave them and use your own wallets exists. Unlike with FIAT, where you are forced to use a payment processor for electronic payments (opting out means using only cash), would you rather be chained to payment processors and forced to accept terms and conditions (some abusive) or have the ability to give them the middle finger?
‘The idea behind cryptocurrencies was to use them as currency. That idea faded when stock market parasites took over bitcoins.’ <- No? That still is. There are still many other crazy people like me who use cryptocurrencies for what they were intended for—not to get rich, but to actually be able to use our money without the government or a corporation taking it away from us.
‘We don't need cryptocurrencies. We need PayPal for blackjack and all that.’ ← Aha. And what does that imaginary system look like? Who's going to create it? How will it work? How do you ensure it remains impartial (or at least doesn't repeat the same thing as with Visa/Mastercard) in the long term? And can it be done globally? How? If the government of the country where it's based becomes corrupt, how do you prevent it from interfering with global payments? Is it a company or a payment protocol? I'm assuming it won't be a protocol, given your anti-bitcoin stance. So I assume you're talking about a company. So, who will run that company? Is it someone trustworthy? How will it be financed? How will it operate? Will it be profitable in the long term? Who will provide the initial investment? Are they trustworthy too?
I understand that many people don't like cryptocurrencies for various reasons. But treating them as if they're the worst thing that's ever happened to humanity is a bit of a stretch. It's a viable solution that exists now and can be used to prevent abuses by both governments and large corporations. I don't want to force anyone to use Bitcoin or anything else. In fact, I'm voting for Itch to do something like "Itch.io gift cards" if they can, and for everyone to buy them however they want.
Let everyone be free to choose.