Islam didn’t grow until Mohammed started ATTACKING others. Very few people followed Mohammed until he left to Medina where he gained in power. What he gathered around him initially were mostly his family, a very few friends and some slaves.
His ‘revelation’ usually revolved around the promises of some sort to keep his men fighting. He had to promise rewards to them all the time, and coerce them all the time because they didn’t always want to fight. He made fighting a holy thing and promised them heavenly rewards to a desert people - rivers of water, abundant food, women and little boys, and even has his Allah a supplier of Satan’s stock of wine.
HIs wealth grew as the more caravans and cities that were poorly armed were attacked and he could steal the goods, and women and children as slaves. His men’s wealth grew, but so did his coffers since he said Allah said he could get 1/5th the loot from any attack. He made anyone who didn’t believe in him as his enemy, and if threatened and bullied anyone who left. He wrapped holiness around atrocious acts such as murder, torture, enslavement, rape, assasination, etc.
At one point he realized that killing off all the non-mohammedan men wasn’t such a good idea because they were the farmers, the traders, and other things to keep life going so he decided to subjugate them and let them know that if they accept subjugation they were to feel subdued, humiliated, daily; and they were to give him and his fellow mohammedans a tax that sometimes extended past death.
I think your version of how Islam is spread is a pipe dream or some twisted version that Muslims have told you. It was spread by the sword, by terror, he kept no promise (cease fire or treaty), he deceived his enemy, he killed the poets who were the news of his time. Basically, he was a fascist and practiced what fascists practice - kill of anyone who disagrees with him, and make them the enemy, terrorize, and lie. He would reward his men for torturing others, tearing old women apart, for bringing him more loot and slaves.
The whole thing is sick.