Smart investors often discuss the importance of doing things or investing in events with "asymmetric risk".

Huge upside, limited downside.

SEO and more specifically affiliate marketing has always been this game. You don't need to be wealthy or put that much money on the line to play, and if you win the upsides are potentially huge.

For example, the costs to start a new site are virtually zero per month:
  • Domain costs around $0.92 per month with Cloudflare.
  • Hosting of unlimited domains with DigitalOcean and ServerPilot is $5 per month for a droplet that can host a ludicrous amount of traffic. 
And what are you risking? 

Time, sure but as you scale you can replace your involvement with a team and buy it back. Literally turning sweat equity into cash and your own personal ATM machine. 

What are you waiting for?