For businessmen:
- You can sell your goods or services for cryptocurrencies.
- You can make and sell hardware for mining.
- You can make and sell hardware and software to companies who make cryptocurrency projects and blockchain projects.
...
For investors:
- You can trade cryptocurrency.
...
For businessmen and investors:
...
I think you should add creating a cryptocurrency exchange as a way of earning money for businessmen and investors are not trading cryptos, they are simply choosing cryptocurrencies which they think are good for long-term or mid-term investment. Trader are kind of a different type of people. They shouldn't care about the project and the future of it, they are simply playing on regular fluctuations of one or more coins. Investor can spend some time on choosing a project and then buying some coins, while trading is an at least part-time job.