I'm a firm believer in a diverse portfolio. The basics apply. Do your homework, don't invest what you cannot afford to lose. Don't buy and sell based on your emotions.
XRP may be centralized, but so is the USD and we all use that too. Stocks, Bonds, ETF, Metals, centralized and decentralized crypto are part of a complete portfolio.
Pump and dump is real, but to me it's all part of the game. If you see a coin, and you like their purpose, read up on it. Research the developers and the founding members. Does the coin make sense to you? If you don't understand it, maybe look at something else. In the end, they are all only worth what people are willing to pay for them.
Plus, it can never hurt to have a few thousand coin (if you can get them cheap enough) in case they blow up in the next few years.