Just what the title says if you have $50k fiat ,will you put on btc or in bank ,which of them will give you bigger profit after 10 years?
The first problem is that if I'd have 50k I'd start with paying my debts to the banks

But let's ignore that and focus on your question as what you meant.
My answer will be: neither.
I'd buy a flat and rent it out. That would be a pretty stable income over years no matter what.
If any money remains from that then I'd consider Bitcoin.
Why? Because although Bitcoin should give much bigger overall profit, it doesn't go linear. And if I need money I may have to sell at a loss.