In cryptocurrency people can get maximum returns but for them it is crucial to understand each and everything about it. It does not mean that by just engaging you will get what you desires but the actual things which matters are the understanding.
They just need to understand how to keep money safe in the form of crypto and what measures to take in order to not accidentally getting scammed. After that just buy and sell high, how hard can that be? Actually it is tough that is why people lose more than they make in trading.
Trading of cryptocurrency is more acceptable than physical money because physical money is not as much higher as that money which is offered through cryptocurrency trading. Trading can be a source of wealth but it can also be a source of poverty because of losing money due to your mistakes in trading field.
Physical currency not being high is a temporary thing that can change, should not be the reason for crypto trading. Today USD is lower than bitcoin, but the average person gets paid in fiat not bitcoin - so for them 1BTC is a huge amount usually not affordable in a single salary payout.
Trading is not for everyone though, those who end up losing money even after playing it safe are doing something wrong and if they are unable to identify it they should move away from trading.