Investment not only comes in the for of money. You can also invest your time and effort in doing bounty campaigns. By joining campaigns you can earn some tokens which you can sell by the time it was listed in the market.
Speaking from the crypto perspective, i would say that as long as you have knowledge about the market and the cryptocurrency, it is not necessary to invest big. Just look at the current value of coins like ETH and Bitcoin, low indeed and a sharp investor would invest in such a time to earn and make double or more than double money for the investment cost maters a lot. And since one quests only to earn money, any asset that promises a nice share of profit in the market should be owned and not only cryptocurrency.