Most poor people are poor because they don't have paying work (i.e. a job or business). In the poorest countries unemployment rates are always very high (50%+) and even if rich countries the poorest are usually unemployed. Without any income basic survival is difficult and it is almost impossible to save and accumulate wealth.
As I pointed out above you could take all of Bill Gates wealth away and only have $19 for each of the 3.5 billion in the bottom 50%. While this might help some in the short run because Bill Gates would have to stop his aid activities many would be worse off in the long run. But more importantly it does not solve the problem.
The only solution is to get the unemployed into paying jobs or businesses. Even the lowest paying jobs on earth, such as Bangladesh garment jobs, pay twice what redistributing Bill Gates fortune would - not just once but EVERY MONTH. Unfortunately making this possible is a lot more complex than writing a check but it certainly helps to better understand what needs to change.