He started from a very honest and opened "I don't know how to cut and use a knife" and ended up overnight an authority on knives.
Hardly overnight. Took him years of hard work and creating content to become accepted as some sort of authority to (some) people. Before that, he was just a guy putting out his opinion/experience to share with others. No different to being a forum member for years and sharing your thoughts and experiences.
He definitely comes off as a bit of a shill these days, however for the most part he probably still sees it more as a hobby than a 'job' and is trying to be honest with his content.
Good luck to him - he reminds me a little of Chris (nightwing2303) who has been reviewing basketball shoes for years. Started as just a dude doing the occasional review to someone who was able to do his own collabs and start branding his own gear. I still watch Chris and think he remains very down to earth, more so than Ricky appears, however they're very similar in that their hobby has grown into a job - be it primary or secondary.