If I had $10M, I'd never work again, and would fill the shop with toys. I already have most of the machines I've ever wanted- with a couple of notable exceptions- so the money would go towards a bigger shop, better support (like native 3-phase rather than rotary converters) and of course the projects themselves.
Now, if you clarify the statement and say something like, you have a $10M budget to get a machine shop together to produce a marketable product, that's different. But then, you'd also need to clarify what product. Few paintball products, for example, would need a Wire EDM.
Or, does the question assume starting from scratch (no machines or tools at all) and what you, personally, would blow the cash on? In other words, what you want, not necessarily what you need for a business or specific product?
In that case, I'd bank $9M or so, in whatever investment instruments would provide me a decent yearly income from interest or dividends. Even just a normal savings account at 2.5% interest would be almost a quarter-million a year.
I'd then use the other mil to build a big shop- like 60 x 100' or even 80 x 120'. I already have a shop roughly a sixth that size, and it's stuffed to the freakin' gills.
Said shop would be on about 10 acres or more, and all the monthly bills would be automatically taken care of through the interest.
Besides the machinery I already have, I would add a large lathe, like a big American Pacemaker, or a Dean Smith & Grace or a LeBlond. Also a larger vertical mill, like a 10x52 with a 40-taper spindle, plus a large horizontal like a big 50-taper Cincinnatti. All well-tooled of course, with various arbors, collets, vises and cutters.
A large radial drill, probably some sort of CNC VMC with a tool changer, bigger welders (my TIG is actually a bit undersized) and probably a bunch of automotive machines, like cylinder head surfacers, boring bars, a line-hone, etc.
Depending on how much money I had left- the building and land would have eaten half that million so far- I might spring for a waterjet, plaz table and CNC lathe too. The rest would be spent outfitting the place with work carts, tool chests, parts cabinets, ethernet, a car lift and a small apartment over in the corner.