If you could only make 0.10% a day you would eventually be a billionaire, even with a small starting balance. The issue is that its very difficult to be consistant.
There are times when Bitcoin trading is easy when we got clear trends and you can just catch the trend but there are many times when there is no volume and it just trades sideways like it does many days. Look at the daily chart and see how many times we had a daily inside close day, its more often then you think.
Hence if you try and trade those choppy days you will most likely get "chopped up" and most of your losses will go to brokerage fees and the spread. So this is why its easier said then done. Its like the stock market, it goes up and down many %'s of the day but its even very difficult catching 0.1% of that move before it starts to move against you and result in losses.
Exactly, compound interest will assure you that as long as you can obtain profits at that level then you will eventually make a lot of money but as you say the issue is the consistency, it is impossible to earn that every single day, you could have a day in which you earn 10% but then you lose 9 days in a row and all the profits that you had got erased because of this string of consecutive losses, the worst part is that it is impossible to avoid those losses since no one can accurately predict the future.