I got Minecraft when it was still in beta, for exactly that reason. I was in college, I had some free time, and I liked messing around with the demo - it reminded me of all of the fun I had playing with Legos as a kid. I think it cost me maybe $15?
Now, a decade later, I still play it fairly often, and given all of the content that’s come out since then, it might be the most worthwhile $15 I’ve ever spent.