This is a fact

No, it is not. The fact is that they made a claim. What they claimed is evidently not factual.

He turned fishermen into scholars and philosophers and theologians. Their lives were radically transformed

They followed a cult leader and got themselves killed for false beliefs. You think that's a good outcome?

I'm not sure you get this. This is like Donald Trump waking up one day, disbanding ICE, apologizing for his actions, turning himself in for those crimes and putting welfare above warfare.

I'm not sure you get this. It doesn't matter how much people like a guy, that doesn't make him correct.

If Jesus and his followers were lying, James and Paul would've been the PERFECT semi-biased-against-them investigators. But they investigated and converted.

They were fooled like the others. Jesus's message was hypocritical, dangerous, and stupid, but he was evidently very persuasive.

If it was a hallucination, why would his tomb be empty and james and paul converted after investigation?

These are three separate things.

The tomb may not have been empty at all, we cannot verify historically. But if it was, I find it more likely that someone took the body than that a dead man came back to life after so much time.

Hallucinations may happen independently of whether the tomb was empty or not. Believers may have imagined Jesus, or dreamed about him, or hallucinated while on some kind of drug. It's also possible look-alikes claimed to be him, or (unlikely) Jesus faked his own death and appeared to them himself. It's also possible the claims are simply false, we have no way of verifying. I find all of these explanations more likely than a miraculous resurrection.

As for James and Paul, it only shows that they were convinced, not that the resurrection was true. And how do we know Jesus appeared to James? Because Paul said so? It's also worth noting that Paul's teachings deviate from and conflict with Jesus's. Whatever he saw, it likely was not the same character we read about in the gospels.

Paul's experience may be consistent with symptoms of temporal lobe epilepsy: https://pmc.ncbi.nlm.nih.gov/articles/PMC1032067/