Who are these people who donated the funds? They couldn't give to someone who couldn't afford a life-saving operation?
Maybe Kyrie Irving sent him some money.
If this guy was so skeptical, and trusted none of the evidence that the earth is round, why would he trust a rocket? A rocket is based on the same kind of physics that led to the conclusion that the earth is round, long before astronauts could see this with their own eyes. This guy put his life in the hands of the exact same process he didn't trust when it came to the shape of the earth. He said he didn't believe in gravity, then why did he need a rocket to leave the earth? And how would he know how much thrust to use if he didn't actually know the strength of gravity?
Did he ever wash his hands? Why would he do that? The main purpose of that is to kill germs, but he almost certainly had never seen bacteria, and had to take someone else's word that they existed. Why would he believe that, and not believe that the earth was round? If people would lie about the earth's shape, why wouldn't they lie about the existence of bacteria?
Was he incapable of understanding that almost everything we believe we know comes from trusting the words of others, that we have very little direct experience of anything?
OTOH, he could have had direct experience of the horizon, when we look out over a vast expanse like the ocean, our field of vision stops at some point. Did he not take this as evidence that the earth is round?