Bread on the table?
Badspot has spent his time to build a game. A very good game that you'll no doubt agree, is enjoyable.
Why shouldn't he be allowed to charge for it?
People in factories don't give their stuff away for free when they make it.
Badspot has made Blockland a buyable game so that he gets income.
Badspot is an adult, adults need money, hence the having to pay to play. It's all fair.
You'd not be too happy if you spent a lot of time on a game and a community and got absolutely nothing back from it.
So Eric made this game just so he could pay for those things?
I wouldn't believe he made it solely for money-making, but money-making is a helpful byproduct from making the game.