When it comes to Bitcoin there are many reasons to believe that the cryptocurrency has the power to create wealth. Even small amounts of Bitcoin have made people incredibly wealthy. In December of 2015, The Guardian reported the case of Kristoffer Koch, a Norwegian who had purchased Bitcoin worth $26.60 in 2009. Koch acquired a total of 5000 Bitcoins for his investment, which at last years rate was worth $886,000.
A nice article that you should read :
https://cointelegraph.com/news/want-to-be-a-millionaire-two-main-rules-of-bitcoin-investingIt is true that if you can see the potential of any cryptocurrency and believe in it then even small amount which you may consider as dead can reap you amazing profit, like what OP has given example when bitcoin value was only in single digit and that time who ever invested atleast 25$ is now a millionaire. So even today their are so many altcoins whose potential are high and in long term you can become rich when their projects are booming it.