What are the reasons for the success of the rebels? Why did the Spartacus uprising end in defeat?

The uprising of Spartacus was unexpected, and the Romans were not ready for such a course of events. Someone from the circle of gladiators informed the Romans about the conspiracy, and Spartacus, together with his followers, managed to get out of the city and climb to the top of Vesuvius. At the foot of the mountain, near the only slope, the Roman army was located, led by Guy Claude, but the Spartans at night descended from the other side of the mountain with the help of ropes from grape vines and attacked the camp. This was the first victory of Spartacus. Slaves began to revolt everywhere, and the army numbered about 70 thousand people.

The uprising of Spartacus ended in defeat because:

He decided not to go towards the Alps, but turned to Rome, although he perfectly understood that he would not be able to capture the city.
The commander-in-chief of the Roman army, Mark Licinius Crassus, severely punished his soldiers who fled from a meeting with Spartacus.
Spartacus believed the pirates, who promised to take them to Sicily, but the pirates deceived them, and they remained on the mainland.
Crassus asked the Senate for help and state troops came to his aid.
Disputes have become more frequent among the slaves.
The Roman forces were better equipped.

The slaves did not have a clear program; there were disagreements between representatives of different ethnic groups. They were undisciplined and not properly armed.