So ya I agree with you there 100%. Once you have the knowledge though I think its really important to try new things. For example I made a ton in Online Poker back in 2005-2007.. Now its nearly impossible to make real money in that industry. Things get hot then saturated. For people doing seo/sem its totally different though.. thats about 10% of my business. 90% is all direct response marketing, ppc.. It is definitely much easier to test new niches with ppc.
How much will you make? I think my best month with Google AdSense was almost $5,000 over the last ten years. That amazing month blew my mind since it was actually near the beginning of my blogging journey. When you go from making zero to $5,000 in a month, that will rock your world. For me, it also got me even more excited because I knew there were other ways to monetize.