The best way to learn is to become a PPC expert at some marketing company, you'll still burn through thousands learning all the tricks, but at least they won't be your thousands.

I haven't fully validated this idea yet, but I ran a Google ad campaign for $5 a day for a mailing list signup page that I was planning a business around. Click through rates were around 2.5%, which seems to be the baseline, i.e. a 2.5% click through rate basically means no engagement. One thing that was interesting, however, is that certain keywords had click through rates around 7%. I wanted to try re-targeting the campaign to just those keywords but I lost motivation.

Generally yes, it's just a different approach. Most people in the Google Ads space actually get their start with warm intros to companies and/or individuals that want to get into digital marketing, and just get a percentage of their monthly ad-spend for contribution. You can haggle with price per lead or revenue share from the leads that convert, but you still need capital to initially launch those campaigns.

When I started out in lead-generation using Google Ads for ACA coverage, Final Expense insurance, roofing and solar installs, I did it in this order:

1.) Reached out to insurance agencies & roofing companies I already knew, convinced them I could do their digital marketing campaigns for a percentage of their monthly ad spend;

2.) Got upfront capital through that ad spend percentage and had the clients manage the ad spend for their own campaigns, and used the ad spend percentage capital to build cost per-lead campaigns for other clients. These were far more lucrative in investment, but cost a lot of money upfront.

3.) Proved my merit for clients in both approaches, and used my second quarter audit to "upgrade" the clients in number 1 to a cost per-lead, and negotiated with clients in number 2 to a revenue share for converted leads.

It's a grind, it's hard, but it can be done.

"is there any way to create a profitable Google Ad campaign without sinking thousands of money ramping up and learning?"

Yes, it's called hiring an expert with a track record who will get you profitable a lot faster than you probably could yourself (assuming you are inexperienced).

They can work well for B2C, wouldn't expect the same for B2B businesses.

I think it is possible, but you can't do it on the freemium model, or very aggressive paywalls for premium features.