It can be a good thing when you can allocate a few percent of your income to be in bitcoin.
But as you said before, everyone has their own thoughts and strategies, when doing it with spare money as long as it doesn't interfere then I think it's also good, it's just that this should pay attention to more conditions where when there are unexpected needs then they should have some policies to make their finances not disturbed in terms of plans.
But when it comes to comparison then I prefer your way with budgeting beforehand apart from we know how much we spend on investment, unexpected needs can be overcome because there is an allocation there in financial management.
I think when you still have 50% reserve budget of the total value of your investment, then your financial situation will not be too risky even if you get a few surprises about unexpected expenses. I've always wanted financial management that way, but so far I've only had 20% of the total investment value as a reserve budget.
So in essence, have a spare budget regardless of whether you can get it equal to the value of your investment or maybe less. If you have a reserve budget higher than your total investment value, then reinvest with the same strategy.