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.
Trading mentality is always associated with short-term activities. I've never seen a trader who withdraw his proceeds from trading and investors back into Bitcoin, they only withdraw profits to spend them because it's the dividends from their trading occupations. Most Traders are not holding, so I cannot believe myself that they can stop trading to live off their profits, at least none of those within my friends circle can. When I spend money from my job proceeds, they spend from their trading proceeds, leaving only their capital behind, which seldomly grows, if at all.
So I find it difficult to believe that while I anticipate that one day, at the end of my holding period, that I may have no need to continue working, but live off my investment, that they too can anticipate as well to live off their small trading portfolios, or the profits they don't hold, but spent immediately it came.
If you say that traders do not invest in Bitcoin or they only use the money from their profits for daily life, I personally cannot say whether this is true or not. Because I'm sure day traders also have an extraordinary interest in Bitcoin. So logically it is certain that they tend to buy bitcoin and invest in it. Because I don't believe that for example a trader is not interested in investing in bitcoin. Because traders have certainly continued to observe the market for years (for those who have been around for a long time), so they definitely know more about the progress of the Bitcoin price every day. That's why I'm sure the majority of traders definitely have money invested in bitcoin. Because it seems like this, their daily trading activity is definitely to earn money for their daily lives (although of course it is not consistent). And traders are also definitely aware of the potential of bitcoin in the future, so they will definitely buy bitcoin, if they have the money.