Altcoins can be profitable, but they come with higher risk compared to established cryptocurrencies. Research thoroughly before investing. This is not a financial advice.
Things depend a lot on the altcoin that one has chosen as his investment vehicle. ETH is an alt but it is a very good one and whose potential really rival that of Bitcoin. Everyday, we are producing more alts on the market vying for people's attention and support with many of them just here for the money and when they got their bags full they will evaporate like a water in the desert. People can then be left with nothing for their investment, time and effort. That is one big reality in this industry that is why one must always be careful and weigh on the possible risks involved when getting into cryptocurrency, alts or even Bitcoin for that matter.