Your fears concerned with longtime investments in alts are understandable. Most of alts are not as reliable as BTC and are bad for longtime investments as they can dump and even scam. However I think that there are some alts that are good for longtime investments. I’m talking now about ETH and BNB. This two alts seems for me really good because first one (ETH) has a huge platform with a lot of great projects based on it and the second one (BNB) is the main alt of the most popular nowadays cryptomarket exchange named Binance.
Of course, the mentioned altcoins have huge potential in bull market season but the potential is limited compared to what can low marketcap altcoins can pay with same investment amount. I prefer to invest in the low marketcap altcoins obviously and the potential pump will cover the previous losses let alone the 10x uptrends.