I presently use an exchange service, that has option to hold in Fiat money as well, such as USD
would this method work.
1. put some money into a crypto. e.g. ETHEREAL
2. wait for it to all go up, the rates to go up
3. withdraw all or just the gained earnings and put into Fiat account as holding
4. wait for Ethereum etc to go down again, to fall
5. reinvest and put in from Fiat account again,
6. wait for Cryptos to go back to green again.
7 repeat cycle
would you consider this as a decent way to make earnings in crypto?
Well, that is the most famous way of making money in the world of crypto. The volatility is advantage for us in the long run and that is what keeping the market very very interesting to play with. The steps you mentioned here is also called as reinvesting or compounding of your profits. The profits which you gain are reinvested when the time is right for it.
This gives you zero loss in future investment because virtually you are not investing your own money, you are juts re-investing the money which you got as part of the profit. :-)
So yeah most of the time this will work surely and you can enjoy the profits but you have to get very patient while working with the complete cycle. You should not be panicked while doing so, you should not get stressed out while doing that. Rest is all your profit!