It is simple empirical data isn't proof. It is as if you were testing primes 2 yes, 3 yes, 4 no. Here is empirical data that only 2 primes exist. Should we believe it?

Sure for Collatz we have tested more than 3 numbers but we can't guaranty it is true until we test all infinity of them, or have a proof that doesn't rely on empirical data. To do otherwise would be to look like a fool when someone got around to testing N+1 and it no longer being true.