Constantine 1 moved the capital of the Roman Empire from Rome to Byzantium because he

Constantine I The Great, was the founder of the Bizantine Empire and moved the capital of the Roman Empire from Rome to Byzantium, which he renamed Constantinople.

The reasons that triggered the emergence of a new capital were mainly related with the decadence suffered by the city of Rome, and were the following:

Rome was too far from the trade routes and lacked strategic or commercial value. Rome was still important but more as the symbol of the empire because it was not a booming city anymore. Rome still required a lot of attention from the Emperor, as the Senate was there, as a powerful authority that had been functioning for a thousand years already. Rome was the center of the old Roman politeist religion. Constantine introduced and legalized Christianism as the new official religion in the Empire, but the largest reticences were encountered in Rome.

In conclusion, Rome was a huge city with required a lot of attention but did not offer huge return anymore. So Constantine just made official what other previous emperors had already noticed (as they had spent little time in Rome). Moreover, Constantinople could offer those benefits that Rome could not anymore.

Tha answer is that He wanted to recreate the glory of Rome in a more geographically strategic location. (APEX)