I don't see any problem, you can hold you altcoins in your wallet for years. It would be safe, if you hold more established altcoins, as there are many shitcoins, if hold them then they may fail in future. But the better strategy is to sell your coins when they are pumping hard and buy again when they crash.
sometimes it depends on a situation.
some people had lost their private keys or crypto wallet accounts so those coins will be gone forever until they could retrieve their accounts.
but most of the crypto enthusiasts, they prefer selling especially bounty hunters because most of the bounty hunters like me have no professional job career.