Followers of Jesus (Christians) were not just persecuted in the land where Jesus walked but in various places around the known world, which, at that time, was mostly controlled by Rome.
In the time of Nero (reigned 54-68 AD), Christians were eaten by lions, crucified, and even burned alive to light Caesar’s gardens at night. Emperor Caligula (reigned 37-41 AD) also inflicted torture and execution upon Christians. Claudius (reigned 41 to 54 AD) expelled the Jews from Rome since they “constantly made disturbances at the instigation of Chrestus (Christ).”
There was no upside for the apostles to have invented Christianity – or for people to adopt Christianity – unless they believed it to be true.