It is very difficult for new tokens/coins to compete with other altcoins and very rarely altcoins have managed to occupy the top 100 coinmarketcaps in the long run. Usually only a temporary hype and after that interested people began to decrease.

diversification is useful for backing up situations, and reducing waiting times.

if we only focus on two coins, especially in large quantities. then the trading pattern will move passively. Your strategy is correct, but it doesn't appeal to some holders who actively monitor charts every hour and also see a variety of fundamental news from coins being held.

We are here looking for altcoin of course in the end to exchange with BTC and save it and sell when prices are high or we can use BTC to buy products and therefore it never hurts to release our altcoin assets to BTC but it never hurts to wait for the moment right to release altcoin, maybe many people who want to return to altcoin in 2017, but all of that is just an illusion in my opinion because if altcoin has reached ATH it will take a very long time to achieve again

I don't think is ok for people who buy at ATH to sell their altcoins now because maybe if they sell they will have a high loss, they can still and wait for a new bull run and we will see what will happen this year after halving.

It would be very easy to dismiss today all altcoins as unprofitable. However, there are many things at play, and when some of those factors have materialized, some of those we initially thought of as unprofitable may moon. Perhaps the better advice is to trade better and hodl those that belong to worthwhile projects. No one can be entirely sure about the future.

Many are simply in frustration because they invested when altcoin was at a higher price in 2017 to early 2018, I get it but its not the end yet, your profits can be returned in folds, if you sell is when you truly lose here, hold your altcoins for now

Everyone is entitled to his opinion though, however I agree with about 90% of what you said. They are the truth and pure fact if only most will take time to understand it. Yes, bitcoin is the best crypto to hold owing to its decentralized nature, at least most can agree that there is other coin so decentralized like Bitcoin. Also, it can't be argued that Bitcoin can do almost all things most altcoins are already doing but I believe only bitcoin can't drive this space, there needs to be alternative thus altcoins. The only issue here is the way these altcoins are springing up with no tangible results to show for. Only few are actually doing well or working towards a purpose. I can't encourage selling all holdings to Bitcoin but holding Bitcoin in large part makes sense to me while the other remaining can be for altcoins one believes in.