I think you're assuming that there is no valuable/monetizable difference between a neophyte, and an experienced expert serving (and supported by) a solid organization.

Also, I don't know where you live, but the more powerful substances used by licensed pest control are regulated and aren't (legally) available to the general public. If you're willing to run a business model based on unlicensed use of controlled substances, there are more profitable options than pest control lol