I don't have any problem with the idea that some folks earn very low amounts, such as $100 per month or maybe even lower, yet I have some difficulties imagining scenarios in which persons at those same levels would be ready, willing and able to invest 80% or whatever into bitcoin.. That hardly makes any sense absent some further explanation, as I suggested some explanations in which a person could have some ways of getting food through farming or services or otherwise having various expenses paid for in terms of lodging - but at the same time, even if some folks might have some really strange circumstances, those do not make very good examples, unless we explain the circumstances, and another thing that I already mentioned several times is that a lot of people (whether poor or not) have really difficult times even investing and/or saving 10% or more of their income, so when we are coming up with examples that are presuming sustainable abilities to invest even greater than 30%, then I am going to question those circumstances, including questioning if they are either sustainable, long term or maybe just trying to play the wave by gambling and using money that you cannot afford to set aside for 4-10 years or longer, which are the kinds of longer term strategies that we are aiming to discuss in a thread like this... . .
I'm also having a hard time trying to imagine someone who earns $100 investing over $80 or more in bitcoin, I mean what's he going to do with the remaining $20 or less, how's that going to cover other expenses, but well except of course the person have already stashed up more than enough money for emergencies as well as his reserve/float. (Especially his reserve) Because that's the only way $20 dollars should be enough to cover for other expenses until his next paycheck.
But sometimes, regardless of how huge a person's reserve funds are, investing 80% of one's income could still be considered to be quite an aggressive wsy to accumulate bitcoin, especially for someone earning such a low amount of money.
Just as you stated, a lot of people struggle to save up to 10% of their income, regardless of their income level, so investing 80% and having 20 left could be pretty much challenging for such a person to be able to allocate it appropriately.