No, it's not. That is a lie microsoft tells the public to motivate people to upgrade.
If you were ever relying on microsoft to keep you safe then you were never safe to begin with.
Get a respectable internet security suite like bitdefender and win7 is just fine.
People and businesses used winxp for years after microsoft ended their support and nothing exploded.
That's a pretty bad example.
EternalBlue affected pretty much all versions of windows, including 8 & 10 which were well inside their support period. Nothing about that was winxp or even win7 exclusive.
Also by the time that exploit came out most people weren't even on winxp anymore. Most people who were avoiding win8 & 10 had long since migrated to win7 which was also within it's support window and was still affected.
As for microsoft not fixing such an issue if it were to happen again...
Your whole argument is that they fixed it the last time something major happened and therefore they won't in the future? You pretty much shot your own argument in the foot as you made it.
If something like that happens again, microsoft will fix it because it's a major black mark on their company if they don't. As awful of a company as microsoft is and as little as they care about their users, they can't and won't ignore an issue like that. It's just too damaging to their company for them to do that.
I've been down this road multiple times before through multiple versions of windows. An older "unsupported version" is not drastically less safe than whatever their current offering is. They certainly would like you to think that is the case since it benefits them for you to do so but it just isn't true.
