I can decide to invest in bitcoin for one
Putting in discretionary income into your Bitcoin investment dosent automatically guarantee an investor more earning. See ehn Bitcoin is not like some kindd of savings accounts where you keep putting in money without having a clear plan or strategy. Cos if you do so you would end up losing more than you bargained for. That is why in addition to having your discretionary income every investor should also have a clear strategy like DCA (Dollar Cost Averaging) coupled with having an emergency funds...... It is only when this three combos are properly applied (which is having a discretionary income, emergency funds and then having a strategy like DCA), that an investor can boast of having more earning but then this earning mostly comes in the long run( 4-10 year+).
Off course before one will start Bitcoin investment journey they ought to have a mental picture of how they want their investment to look like because you can not just wake up and said you want to start investing in Bitcoin. Everyone is investing to have a portion of Bitcoin and also to make profit in the long run so it is something that one should be diligent about.
If someone have a good discretionary income and they are not making or utilizing it well it is same thing as someone ( investor) who doesn't have, we are the one that will make our investment look great by our action.
I believe all strategy are clear it is just the way we perceive things that matters though DCA method is very good in the sense that everyone can invest using it.