A lot of traders are dumb to believe that they are able to consistently make money on trading in order to be able to live off of their trading. It likely would be best to have a separate income so that you are building up your trading capital and experience, and sure if you have two accounts, then you can also build up your investment capital with your other speparate income.
Sure, if you are able to build up your experience and your trading capital to a certain amount, then maybe at some point you will be able to withdraw some profits from from your trading account, but it seems quite unrealistic to presume any kind of an ability to live off of your profits from your trades, especially in any kind of consistent or meaningful way. Many traders work pretty hard to build up the capital in their trading account(s), yet sure, I am not going to deny that traders may well have unrealistic and dumb fantasy ideas like you mentioned - a belief that they can actually draw income from their trading account (and trading activities).
Edited to clarify
You are right, many traders fantasize excessively about living off their trading results. Although this is not impossible to realize. But I also believe this is very difficult to do. Because trading is not as easy as we imagine. Maybe many traders misunderstand this ideology (buying when the price goes down and selling when the price goes up). If you don't think about it, it sounds easy. However, in reality this is very difficult to do perfectly. Therefore, to be able to realize consistent profits from trading, in my opinion, will be very difficult. Because apart from that, traders are also sometimes manipulated by whales who have a lot of capital. So for these reasons, I don't think becoming a trader is the right choice. Because being a trader really takes up a lot of our time and also has the potential to waste a lot of our money. So it's better to just invest in bitcoin if you have cold capital. Because investing in bitcoin will definitely feel lighter on our minds.