Being a full-time trader may be reliable but we must always remember that the crypto market can change at any time and we must also be prepared for that. As long as we are not influenced by negative news outside, we can analyze and determine when to enter and exit the market.
Being a full time trader must be the most tiring career ever. You cannot take a break from it because you need to constantly check the market and any news that concerns your trade. And you cannot say it is reliable since you can get rekt as easily as you can make money. One minor mistake or a sudden bad news can get your profit from positive to negative in minutes.
Trading is not for everyone. Sure there are some who thrives in it but I would not recommend it to someone who have a weak heart.