DevOps/SRE here. Also in Canada which changes things a fair amount compared to the US.

• Finding clients is hard
• "Contracting" where you're an employee except classified by the company as an hourly contractor doesn't pay that well. I.e. they'll give you the same or less hourly rate you can make on salary, but without all the perks of a full time position like benefits, bonuses, vacation, etc.
• Double up on healthcare benefits
• Equity, RSU, etc - don't get these as a contractor.

Specifically for my field... Big companies (F500 and the like) pay trash compared to tech companies.

Tech companies usually want someone in-house. Big companies often employ contractors to augment staffing and not show it up on their budget. Tech companies don't care about budget and treat DevOps engineers as developers, and see it as growing their core business.

Now, there are lots of smaller startups who might benefit from having a part-time DevOps. But those willing to employ a third-party contractor (as opposed to just hiring an engineer) are also those operating on a shoestring budget. So now you're competing with Indians on Upwork.

In the end... just not worth it.