Definitely, alts can be more profitable. From the current price, BTC goes to his ATH 5x. But for ADA, for example, it ATH more than 10 times. And I wait for a higher price for Cardano. Yes, I agree that it will not happen in this year. And at 2019 it will be very difficult. But alts has more opportunities to grow. It's a fact
Watch on the DACC as another example. Current price is 0.5x from ICO. If they will be listed on the big exchange I'm sure price will make 3-5 times.
It is only estimation of normal people that Bitcoin will reach to 5X as we think that it will reach to its previous ATH value while the expert speculate that Bitcoin will reach much higher than the previous year ATH price. So Bitcoin is also beneficial like other coins.