There is no Actual amount of profit you can make investing into altcoin , But the reason why people are choosing to invest into altcoin is that we believe that one day bitcoin will hit 200k and when bitcoin hit 200k our altcoin will also hit 1k and 2k which can help us to makes more money now that most of us are not able to purchase one full bitcoin .
Moreover altcoins have higher growth potential. Thus they are more interesting for investment than Bitcoin. But do not forget that altcoins also have much more drop potential than BTC