There's no fixed profit, the only thing you can make fixed profit in cryptocurrency is you buy a stable coin and stake it to earn like 5-20% APY. Since it's a stable coin where the price always stick with $1, you can calculate the profit as long as you're not get scammed.

How long you will invest in cryptocurrency to buy an apartment? right now the cost is $130,000, but in the next year maybe the price will increase to $150,000.