It could take a person 10-15 years or longer to just build a decent portfolio size, since even a person who had been investing 10% of his income into bitcoin, it will take 10 years to just get to a point of having had invested a whole year into bitcoin, so how aggressive a person is investing and also how the underlying asset performs (in this case bitcoin) can take a decently long time to build and start to feel as if the BTC portfolio size is starting to become a sizable investment amount that reaches a level in which the person might start to be able to lessen his level of ongoing investment into it.
I agree with you investing sustainably would be good to do in bitcoin especially at the age of 30 where he can program discretionary income to continue buying bitcoin for the next 30 years. That's good to do because he can enjoy the results of his investment at the age of 60 and I think it would be good to apply now for anyone who wants to plan for long-term investment.
And it's true sir, building a portfolio certainly takes a lot of effort and no less than the level of perfection of DCA 4 times a month and it must be done routinely. Beginners must run investments at the beginning with full consistency to achieve better results in their first year of investing.
If I want to give an example, I still say El Salvador as the main example of executing bitcoin with full consistency because they continue to accumulate and build a portfolio very well.