As for the plethora of altcoins out there, and, in particular, the few that I own, I worry about the long-term future of their viability. At the time of this writing, it seems as if the sky is the limit and these projects are not only growing, but here to stay. However, things aren't always as they seem and I'm starting to wonder if it may be more prudent to dump and invest solely in BTC which I feel provides the most benefit to society and potentially has the most durability.
I wouldn't say it's prudent to dump altcoins and invest only in BTC. Diversification is important always in investing. Bitcoin is the King though, and if you are holding over the long term I can't think of a better coin to put your money in. That being said, a little exposure to coins like ETH & BNB that can provide revenue through staking isn't a bad idea. Coins that offer exposure to liquidity pools like CAKE & UNI are another great way to provide some revenue for your portfolio. Additionally, you can use platforms like CoinEx to provide your own liquidity pair of coins you choose to deposit.
I guess my point is that crypto is full of cool stuff if you look around for it. Holding is great, but remember to keep some coins to actually use as well. If you're buying altcoins and not using them, that's when I'd be worried about their value going to zero.
My investment method is to hold Bitcoin for a long time. I will also choose some altcoins (I will not put eggs in a basket). For the choice of altcoins, I prefer the DEFI sector, and I will not touch contracts , Use leverage, etc. My method is very simple. The profit rule I set is to rise 10 points to meet my psychological expectations, and then sell.