Heyo. My thoughts:
1) Mining/Staking/Masternodes
2) Airdrops/Bounties
3) Shorting w/ leverage
4) Arbitrage
5)...
6) MacDonalds
Anything else?
The most experienced players of the cryptocurrency market are able to earn good money even in a situation when the market falls. However, today I do not know such sure techniques for myself.