They have just pulled the numbers out of nowhere. As for why the prediction is so far in the future, I could image it being so they can get paid to list other predictions/make other shit coins themselves and predict those for far in the future too as they're less likely to be disproven (I guess).

If you're buying a coin worth 866 nano dollars now that's going to be worth $20 in the future, most people will probably buy as many as they can rather than working out that $1 is probably a reasonable amount to waste on such a thing (at most - though the chain or liquidity pool will likely die/dry up before 2050 too).