professional's won't take you seriously unless you charge $50 minimum per year, probably closer to $100.
Maybe I'm wrong, dunno about price points, I do know I find it quite easy to support someone on Patreon with $5 per month if I find the content valuable. And this should not be viewed as more valuable, people are not constantly looking to switch jobs or take on more work, for many it would be pretty passive network (as is LinkedIn).