Back in the dark days after my cousins had introduced me to DnD and most of my time was spent wargaming a certain British company’s flagship products, I found Warhammer Fantasy Roleplay. This was not the same version that is out now; it was published by Hogshead Publishing and was a far cry different from anything my gaming group at the time had played. Being the only person who had ever played a pen and paper RPG, and being the only person who was interested in doing so, it fell to me to organize, run, and convince others to even try playing my scenario. The ensuing campaign became, without a doubt, the most bizarre campaign I have ever been involved in.
The problems should have first been apparent when the players could not stick to a set schedule. One player was available for every session, while everyone else had other commitments which ensured they could not make it to all of them. This would have been fine enough except for the conflicts that erupted almost immediately regarding the differences this quickly gave rise to over experience differences. It became almost no fun for the players who were lower levels then our ever attending friend, and he took offense to them being leveled up just to be at his level. The jury-rigged solution was to heap loads of magic items on the lower leveled players in an effort to keep them up to speed. You can imagine how that went.
The next problem was the issue of the story. Where I had planned a dark fantasy where the players would be able to overcome their own problems in life to rise and become heroes, they had other plans. Well, not really. In reality they had almost no plans at all aside from amassing the largest pile of wealth, magic items, and concubines that they could. And a flying castle. They had to have a flying castle. I suppose they had been reading Dragonlance at the time or something. Being the young man I was, and not realizing that sometimes bad roleplaying was worse then no roleplaying, I was repeatedly browbeaten into cow-towing to player demands.
By the point I had decided that enough was enough, and god damnit lets just go back to playing wargames, the situation had deteriorated significantly. One of the players was a vampire, halfing, wizard, wearing magical full-plate armour, who commanded the aforementioned flying castle. Another was a half high-elf, half dark-elf, ranger/wizard who was capable of disappearing, communicating with and convincing almost any animal to help him, who rode a wyvern. The third (who was still around at that point, they others had quit ages ago seeing what was coming better then I did) was a normal human who had rolled the dice so poorly for his stats that he had been unable to take a starting job. Instead of re-rolling like I offered, he proceeded to play a peasant who operated similar to a squire to the other players. He was still wandering around the flying castle filled with an army of orcs, kobolds, lizardmen, and much more (oh yeah, they had convinced me they could build an army and had spent several sessions doing so) wearing the rags from his first session and had become the most famous nobody in the world. At this point, instead of seeking to use this huge army to fight evil or change the world or something they simply wanted to dick around and make more money.
And that, my friends, is how you do not convince people to play RPGs.