Yes, altcoin is really worth investing. With their potential growth, it is sure to give a lot of profit in the future. Also, with the price of altcoin being cheap or affordable, we can easily invest, hold and wait for the market to recover.
In general, the cryptocurrency market is worth to invest. I think when you decide to buy, you should research carefully about crypto you want to buy. You have to define what you want to invest in long-term or short-term, and then looking for potential cryptos in the market at Coinmarketcap.