Quite a few people on here push for only investing in 'B class' and I'm sure the statistics support that on a large scale.

I've grown from starting out house hacking to now being financially independent on rentals. 

Great idea to get your next place and keep the original house to rent out and keep doing that for a few years you’ll have an awesome real estate portfolio and well on your way to financial independence.

I've spent several years now writing software to help myself (and to educate potential clients and clients through classes, podcast episodes and books) model real estate as a  tool to achieve financial independence and to fund retirement.

By trade I’m an experienced investor principal, expert creative problem-solving-independent RE and financing consultant —always focusing on planning and execution of real estate wealth building programs for clients in their best interest.

Or past tenants are now owners and they don't have a need for rent.Some areas have good Realtor Associations that keeps the statistics up-to-date, so you may need to do a little research.   

If it’s not an independent investor, it’s wholesaling companies.

I'd prefer to be able to operate independently from that money.) 

I have been thinking for a while of how to switch careers or to gain more independent income so I can afford to not work so hard where I currently am.

Do your same job, or something close to it, but as an independent contractor for more money.