I know this is opinion-related topic and I shouldn't consider your answer as financial advice. Anyway I'd like to see what you think about it and what you would do. Even better, you could reason why you think this way.
This is a good start.
Now, you probably know that Bitcoin (and altcoins) prices variation/volatility is big. This makes Bitcoin an interesting investment if you have money you afford to lose, but not "safe" as "savings account".
Bitcoin price, on long term, should grow a lot. But there are big falls too and there's a risk that in the moment you need your money the price is lower than when you bought.
Of course, you can be lucky and get rich by buying Bitcoin and catching the best moment to sell. You or your kids..
Edit: I would probably buy Euro, Bitcoin and maybe gold too (although I'm not sure it makes sense for 2-400$)