The Gates Foundation does great work. They are certainly one of if not the most effective anti-poverty charities out there. But positing a world "much worse off" is stretching things. Even huge charities are dwarfed by the sizes of governments. Almost all aid is delivered by governments. How much money has the Gates Foundation spent in total over its decade or so of work? What is the USA humanitarian aid budget for a single year?
Again, my point isn't to diss Bill's charity work. But arguing that we should tolerate abusive monopolies in our tech industry because the owners might one day get rich and give the money to poor people is ... borderline insane, honestly.