I hope at some point it makes financial sense for a company independent of software to maintain stuff like the BSDs and what have you. Ie toyota doing something like Netflix. Maybe an embedded devices manufacturer...
They exist to let people watch movies/tv, and use tech to provide that service.
Compare that to say HashiCorp who release tools as MPL and then provide further features under a licence to fund the business; Or Percona who provide enhanced forks of MySQL under gpl (because that’s what upstream dictates) but then additional tools under eg BSD license, and provide consulting for either their own or other database engines to fund the business.
Heck my own business is effectively consulting, but I build tools to make my life easier and release them under permissive licenses wherever I can (If I fork an existing gpl licensed tool to improve it clearly I have to use their existing licence)
It depends what kind of experience you mean. I started working in a 'classic' (i.e. windows desktops and Novell servers in a private WAN) network/systems support+admin role in 2003, moved into web development in 2006, and then gradually got more involved in ops again until about 2013-14, when I started taking on new clients directly (only the very first job was I an employee - in every other position I was essentially a contractor - initially through agencies and then directly invoicing the company).
The income question isn't as easy to answer - my rate varied a lot from roughly what I'd been contracting at for some 'mates rates' clients, up to nearly 4x the price for others - but as is expected it wasn't consistent. It's been a couple of years of pretty steady work at a reasonable rate so I guess the "TLDR" answer is 3-4 years.
Keep in mind, apart from the first 2 or 3 jobs I had (2x government and then one at a Telco) everything else has been 'remote', and I've been geographically remote (I live in Thailand) since before I started this business. I have no doubt this has affected the number of potential clients, but it sure beats commuting into a city every day.
I hope that helps and isn't too much of a ramble. Feel free to email me if you want to discuss it further, my address is in my profile.