Although we all know very well that bitcoin has a strong foundation and shows strong promise of continuous good performance, It is important you know that your investment into bitcoin has no guarantee, same reason you are advised to invest into it what you can afford to loose so that at worst, you would only loose 100% of what you invested into it.
Since you already know that bitcoin has a strong foundation and shows Strong promise then why are you still finding it risky to invest with a higher amount? Even if you can
't take such risk there are a lot of guys out there who are risking big in this accumulating journey, if you're talking about investing with what you can afford, then why is it that most guys always struggle to get to the status of overaccumulation? Seems you're mistaken bitcoin investment to gamble or trading that one is advised to stake what he can afford to lose, but you should know that bitcoin is not even related to this. I don't mean to argue with you on the fact that bitcoin investment is not guarantee, but the word
(investing with what you can afford) is not considered necessary here. I think this advice can only benefit those whose intention is for short term profit, since they're going with the wrong approach.
However, With the DCA method a guy can decide to go with any amount which he know that he can be able to put into bitcoin either weekly or monthly until he get to a point where he feel like the amount of bitcoin which he accumulated is enough.