Honestly as someone who has to brace themselves for parental retaliation every time they spend even 99 cents on a game, I genuinely feel scammed. Good for all the people in the comments who aren't in financially abusive situations who can pay for the same game twice, but not all of us are so lucky. I'm not entitled for wanting the game I paid for, and to suggest that shows you don't care about us. Good luck, I don't know how the rest of the commenters still trust you.
"Now, I want to make it clear that I am very disappointed in the attitude of many of you who shamelessly call yourselves “supporters” when all you care about is consuming a product and demanding more." If this doesn't apply to you, then they're not calling you entitled. The fact that they apologized to everyone multiple times and attempted to make up for it is already proof that the creator cares. I'm sorry to hear about your financial and familial issues, but you shouldn't be mad at an honest mistake like this. The reason this situation is an issue for you isn't because of the price, but because of the consequences of buying this game within your own personal life. You can do whatever you want, but the problem here isn't the creator, it's your parents. They might be responsible for you having to pay twice instead of once, but they're not responsible for the severity of this action within YOUR home. Other people find this forgivable because to them, 3 dollars isn't a lot. If it were 30 dollars for example, it might be the same for them. You're the exception, not the rule.
Considering the Steam release is an entirely different game, and you have the itch.io version, you got the game you paid for.
It's unfortunate If you're in a situation where such little money causes so much issue, but even still I couldn't see being comfortable asking to revoke the financial support you've already given just so you can have what you want, especially considering now the itch.io version is going to be a collectors copy now that it's unavailable for purchase.
It's natural to feel disappointed because they originally promised that the Steam version would be available to those who purchased the itch.io version, but the game blew up in popularity and refunding everyone who purchased, or giving free steam keys, just isn't something we should expect from a Dev, especially if you actually enjoy their works and want them to make more games or projects in the future.
Your terrible situation of not having financial freedom isn't because of the dev, this is a low cost to have access to a new experience, you should be upset with your home situation, not the creatives you claim you wanted to support.