Single most valuable resource: Bug Bounty Hunting

As a Bug Bounty Hunter, what is the single most valuable resource (course, blog, cert, book) that has boosted your skills the most?

Book: @vickieli7‘s BBB + @yaworsk‘s WH101 + RWBH Blogs: @InfoSecComm

Courses: @OffensiveHunter + @NahamSec + @HusseiN98D + @theXSSrat

Platform: @PortSwigger‘s @WebSecAcademy + @snyff ‘s @PentesterLab + @zseano‘s @BugBountyHunt3r

PS: Got all of them for free;)

Methodologies: Reconnaissance: @Jhaddix + @harshbothra_ + @zseano

YouTube Channels: @InsiderPhD + @codingo_ + @stokfredrik

Computer Science Fundamentals: @geeksforgeeks

Getting started in BBH: https://www.youtube.com/watch?v=hDYqWZ11njU