I want to find out why everybody wants to invest in altcoins, what I want to ask is, how much money did you get from altcoins so far?
Going by your question; i'd say that it depends on a few factors such as;
The solution the project is providing:
If the project have a well needed solution in the society; they'll have loads of people yearning for their token. While that will maintain the stability of a coin, there is a tendency for a consistent rise in the value of the coin.
The competitive advantage they have in the industry:
Where there is a competition in the industry, the competitive advantages will make them to become favorites to clients and hence; increased patronage of their services; which will no doubt have positive impacts on your investments when you buy into their coin
Your knowledge level in cryptocurrencies:
This is what will make you to even spot the right coin in the first place and know when to HODL and when to sell. With a very good knowledge, you'll do very well in the market
How much you have to invest
With the above highlights addressed and raring to go, the capital you have with you will go a long way in helping you maximize good opportunities.
Take for instance an investment that have 200% return on investment; someone who has bigger capital will make more profit from the other that have minimal capital.
This goes to show that the amount someone can make will always vary.
There is no rigid valuation to that as far as cryptocurrency is concerned