invest in what? altcoins? no never. at least not as long as there isn't any altcoin worth investing in. until they start creating projects that are innovative enough to have some sort of long term potential, i don't see anything changing for altcoins being pump and dumps.
in bitcoin? of course! bitcoin has long term potential as its adoption is growing and more importantly since the adoption that has happened so far is still so tiny (less than 1%) and it is actually used in the real world not just traded on exchanges!
I hope you are not talking about all altcoins, because Ethereum, Monero, for example, are also altcoins. This is good and developing projects. But in fairness it is worth noting that all sorts of garbage coins really spoil the reputation of the entire cryptocurrency market. I agree with you that Bitcoin is the most worthwhile cryptocurrency and investments in it should be at least 50% of the total deposit.