Yes, it's not possible to have those 1000% to 100000% returns again with Bitcoin and someone who understands the market knows that fact very well. I don't expect to see Bitcoin going 10x or even 2x easily even in this bull run because it won't be an easy thing to achieve. Now, Bitcoin isn't a low market cap asset it's already a pretty high market cap asset and that's why even thinking about getting 10x return faster with it within a few years is a sign of pure stupidity or day dreaming. And, when it grows more in market cap then it will surely become less volatile as compare to its current condition.
It would be unrealistic to expect 100x returns on bitcoin investments these days, but expecting 2x or 5x returns is not impossible. It is true that bitcoin has become bigger and its price is not cheap anymore but if we compare its capitalization with other assets or financial markets. We will see that bitcoin is very small, not as big as we think and the growth potential is still huge.
Gold market capitalization is over 17 trillion, total financial market capitalization is over 100 trillion while bitcoin has a capitalization of over 1 trillion and the entire crypto market is under 2 trillion. So it is still too early to say that it is too late to invest in bitcoin or it is not possible to make big profits from it but it will probably take more time if we want to make big profits.