What a tough question. Even if someone gets paid in some bounties campaigns, he mostly receives tokens, not bitcoin or ethereum in order to directly deposit to an exchange. He still needs a small amount of fiat money to buy gas (commonly ETH) in order to deposit tokens to a specific exchange and then sells them.

Luckily, Bitsgap is the rare cryptocurrency exchange allows demo trading feature. All you neen is to open an account and switch to DEMO mode: https://bitsgap.com/demo-trading/. Other than that, new exchanges usually have bug testing bounties in its pre-run phase. The purpose of bug testing is to find trading system's faults but participants can enjoy the feelings of getting free accounts and trading without loosing money.

There's no safe haven in bear market, except for USDT or any other stable coins, providing that you had a nice cash out before market went down. The only thing you can do now is to choose your action. If you are holding bitcoin, then keep track closely on good altcoins and buy them at decent prices. Remember to spare some bitcoin to DCA. If you're holding stable coins, do the same thing but with bitcoin instead of altcoins. And if you're holding altcoins and loosing money, you're a poor trader for not knowing to cut losses.