They already got your money when you bought the game for your kids. They don't care whether or not you ever play it again, and in fact their server costs are probably lower if you don't.
How do you know they got his money though? Minecraft was released in 2011 and Microsoft bought it a few years later. To me it seems like Microsoft want people to buy their Minecraft spinoff, so they are making it harder to play the original game.
Pretty much. I bought the game ~10 years ago and didn't want to migrate to a Microsoft account, but I have no recourse. They don't care. So I can't play anymore even if I wanted to.
There's an in-game marketplace where you can buy a number of cosmetic upgrades and such with "Minecoins", which are sold similarly to other in-game currencies. Looks like $20 for 3500 coins.
But I thought this forced migration was for Java Edition, and that Minecoins were only for Bedrock Edition.
microsoft purchased minecraft to get an "in" with things kids were actually doing, not just for money. They do care if people, especially kids, continue to play.