Thanks so much for this detailed perspective. Taking notes. ;)
I totally see the counter-productivity in hourly billing. It's never sat well with me. In the end, clients want a final number more than some estimation of time × some price per period. It's just not cognitively the same to drop a final, single number (with conditions, a tight contract is also a benefit to both parties because nobody likes surprises).
There's also this argument about "price for the value it has for your client, not for the cost of your work". Which makes sense in a bubble but like most pop philosophy I feel it ignores that you're not alone selling the service, and agreeing to keep prices artificially high is generally called racket by most ethics, if not laws. (half-jokingly saying this, light-hearted but there is abuse in some domains)
The matter of the fact is nobody likes, again, paying twice the real cost of something for no good reason (today it's you billing, tomorrow it's you paying for accounting or legal or your freaking dental and car bills). There's a slippery slope there that I'm not willing to contribute to. I think it's just not sustainable, in this model businesses are soulless and die like crabs in a basket, and the customer + taxpayer (all of us, all of them) looses the most.
If I'm gonna bill high, it has to be because the work is genuinely harder or better, and I'm very much factoring "past years" in the how/why. It's hard to put in words, even between us technicals, let alone client profiles. It comes down to a scarcity fact: not many people can do it as well, and that's the price in dollar of the time of this small subset.
And indeed I don't think it's "$300 per hour" (that value is computed after the fact, it's a statistic!) It's one deliverable, reduced to a single number (from which you derive the others e.g. time frames, support cost, price of additional features, etc.)
It should basically be whatever a bigger business could earn selling the same product/service, minus overhead¹ and shareholder profits²— all for you, times some scarcity factor. If an employee makes an average $100K making it, we can see a freelancer making about twice as much for the same work (a factor of say 1.25 to 3-ish, this from my a#%, armchair intuition / business angle).
In actual geographical market forces, I see a lot more money going to whoever's established as one of the go-to's than an economist's account of what should be. Reality checks and all that. You need to know X, Y and Z (people, competition, client aggregator...) and go from there. Online is a bit more "opened", but far less than people would think. In a given niche, many people know many people. No niche = low multiplier factor (because low margin for all businesses, includng you), and low bonus (because low barrier of entry usually means less valuation as a market relatively to others).
Best advice I've ever heard: go to business consulting meetups and talks. These people totally understand that you come in with a skillset to offer services, that's the spirit. These people give the single most trusted recommendations, that's their actual job!
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1: you also lose the larger skillset covered by a business team, I think overhead is actually worse for a freelancer if you don't outsource as much as possible (everything that's not your domain, may be better served, more efficiently too, by a professional of that domain).
Tangential but, this is my problem with all the pop-culture around entrepreneurship telling you to learn it all as if improvising ever was a good long-term strategy...
Recruiting solid, reliable, trustable suppliers; creating a synergy of behind-the-curtain business deals; these are much more valuable skills for sustainable success if you ask me. Learn to play with others, combine strengths and values.
2: this is where domain value plays in, e.g. bonus value for a freelancer in fancy biotech versus common web / mobile views.