No doubt that if you are investing a bigger amount then your profits will also be bigger but this does'nt means that the investors who can afford only a small capital to invest , can't make profits in crypto.It simply depends upon the skills and experience of the investor.If the investor is not that much skilled, he/she can never earn profits even by investing a bigger amount. If an investor is investing a small capital at a right time and is having enough patience to hold until the prices rise to a good value and then selling it, then no one can stop him from earning big profits.
One problem of having a very small capital is that the fees are going to become a real problem, not only transaction fees but the fees of the exchange are going to become a problem and that is seriously going to limit your ability to profit, so in my opinion the lowest amount of money that you need to begin to trade in this market is a few thousand dollars which is still a lot lower than what you need to trade in the forex or stock market.