To point out a few things.
The idea that one can make an AAA game and not pay for the good stuff, and meaning no disrespect, gives me a chuckle.
If you make “anything” as a product for the Unreal 4 engine and make a return of $100,000 bucks in a year I say good job…dame good job.
$100,000 is an arbitrary number as to a fixed point as to a rate of return.
With in a context.
If you release your game on Steam and with in a week your rate of return is $10 bucks your game will probably lose focus on Steam.
On the other hand
If your rate of return is $100,000 week then for the year is $52,000,000, with out considering falloff.
Angry Birds is said to gross 1.2 million per month and Rovio Entertainment having a market value of 4 Billion.
Epic only makes money when you make money so your up front costs is zero
Unity’s licensing and support becomes foggy as to up front costs from paying for product support or licensing fees for out of scope use (IE fair use that is not game related)
Unreal 4 product support is free and the scope of the royalty is limited to video game development. Out of scope in this case would be using UE4 for example as a real time rendering platform to produce a full length animated feature film for which you would not have to pay royalties.
Up front cost will kill you and could land up losing money.
As a business you do not want to own your gear or equipment as you can write such items off as a business expense or even as a loss.
Rule of thumb is always consider companies that sell off the shelf software products as being snake oil sales man and learn to amortize your costs.
Last bit of advice, and secret sauce of Indy development, take a few small business course usually offered by your local collage or university…and of course write the fee off on your taxes.