Depends on many factors, the technology, the business, the team. It is safer to invest in top coins since it has a more solid business compared to other coins, the lesser risk. Still, no one can predict what can happen in the future, even bitcoin might die out. We can never know.
We'll never know whats going to happen for the future of altcoins it can turn to shitcoins for losing its value or stay because it has progress still. Op is right, always take profit if we had a chance because the price is unpredicted. I have alts that I bought 2 years ago, it has value but not acceptable to sell, im still waiting for the right time. Now I regret not selling it before when the price is good to take profit.
I think almost everyone has experienced this, regrets not selling when the price has started well and thinking that the price will continue to rise. This also happened to me and I still hold a few altcoins which are now very cheap when compared to prices 2 years ago. But regretting it is useless so we better be patient and hope the team will do something that can make the price back to good