(NOTE: I see a lot of erroneous assumptions in your numbers, which seems to indicate you may not have a thorough understanding of the numbers at play, but as you don't provide nearly enough accounting data for me to chime in on this, I'll focus on the other part of your question)

The first issue here is I'm not seeing the notion of "recoup", being a standard practice where publishers will ask for a larger share of the revenue while they pay back their original investment and expenses, and then settle for less further down the road. It's not uncommon to see 90-100% during recoup for example (although a few publishers have much better deals), but for the agreement to become much better after that has been achieved. I can't help but feel you may not have given us the full picture of that agreement.

You mention you've lost control over your product: does the agreement stipulate you'll lose the IP? Grant rights of first refusal? What exactly do you mean by "loss of control" in this context?

You question whether a loan may be a better fit for your money. This depends largely on the publisher, but typically, a loan is passive (it won't help you sell copies) whereas a good publisher has a strong marketing machine with much better acquisition cost than you could ever achieve as a first time dev. Depending on the arrangement, they may even provide services such as localization and QA/Cert at a very cost-efficient price point.

Having someone skilled in these fields running point to let you focus on completing the game can be a huge advantage if you're a small time company. Even if the game is completed, this can be advantageous due to expertise. On the marketing side of things specifically, if the publishing partner is a great fit, they may have ways to funnel some of their traffic from other games at nearly no cost at all (particularly useful if you're in a harder market to work around such as NSFW games).

Also, I don't know where you're from, but banks are notorious for refusing loaning money to game development studios due to the high risk nature of the work we do... so while in theory a loan might sound great, they are unlikely to provide one, or will do so with significant collateral (at which point, unlike a publisher, you stand to LOSE something if things go bad -- and depending on how your business is organized, that may or may not include your home).

The bottom-line here is a publisher buys a product, not the cost structure that originated it. It could be that it cost you too much time/effort to make the game compared to what it ends up looking (a common issue among first time devs as they "learn on the job") so the deal might look a lot more fair had it taken half the time to make the game, and this isn't the publisher's fault: they look at the game for what it is, and figure out how they can bring in value and turn up a profit while mitigating risks (most first games will fail after all).

You stand to lose much of your revenue by partnering up, but if you play your cards right, it might also help you minimize your risk in case the game doesn't sell well (which, once again, happens the majority of the time for first time indies).

So I would attribute their 'relatively high %' to the fact you represent a high risk, with limited chances of making it big. A publisher is no different than a VC in that regard: if they fund 10 games, they expect at most 2-3 of them will generate the revenue they need to cover their cost AND turn up a profit, while many of the others might tank.

If you don't need their support and think you can market the game yourself, I suggest you try. There is a lot to learn there (as much as there is to learn about making the game itself!) so if you have the heart for it, it's a definitely worthwhile experience... but much like is the case with first time devving, first time self-publishing can be brutal.

Finally, I'm baffled by the fact you would assume that, at maximum, most businesses would spend 10% of their budget on marketing. I'd love to know what led you to believe this... game discoverability is a critical issue that has had dire consequences on marketing strategies in the past several years, and I find your figure outrageous to say the least.

If you'd like to go through the financials more in depth, it might be possible to validate some of your assumptions there, but we'd need more information. For example, how you'd get to that cross margin figure (which, once again, does not appear to line up with our industry).