Anytime one delves into the topic of business, one has to take into account that one of the things you 'use' is people. People are unpredictable. They are greedy, jealous and dangerous to invest in. Even if Peter went into business for himself, who is to say his formula wouldn't have gotten into the wrong hands.
It's the exact thing that characterizes Tony Stark. He is a technocrat. He takes steps to ensure that his tech won't be used against him or for unintended purposes. If a guy with a bottomless checkbook couldn't do that (which why the Stark Wars happened), what makes you think a poor student from Queens could do it ??? It's all about risk vs reward.
But let's follow your example for a bit. Suppose he went into business for himself. If the formula somehow made its' way into everyday lives, there would be people interested in a counter formula to dissolve it. Cause that's how people are. Green Goblin actually FOUND a formula to dissolve the webbing. Used at the right time, something like that could kill. Lots.
And even if we did involve the fantastic four into this, guess what. The FF have a 1st class engineer, wizard, chemist and scientist as their fucking archenemy. Hell, Doom created a time machine ! How hard would it be for him to figure out the formula ???
Besides, there are substances in the Marvel Universe that when compared to Pete's web formula make it seem utterly worthless.
When Peter first tried to sell his formula to someone, he was 15 years old. Smart but still underage. He still was fresh from the mistake that made him adopt his power and responsibility creed. He just came to realize that since a normal teenager's actions can go a long way, imagine what a superhuman's actions could do.
And no, wanting to help people in whatever way you can is not a complex. The driving force behind Peter's actions was always guilt.
Now about the real world arguments: maybe the writers didn't like the idea. Or how about the fact that we arguing about facts in a world where glasses are considered a disguise ?