We think of “much” as a measure of part of a group of things, so it has a plural feel to it, but it’s a singular! (The equivalent plural is “many.”) So we ask, “How much is enough?” But take a look at this sentence, taken from Bruce Schneier’s book on cyber security, Click Here to Kill Everybody, page 147.
So much of Internet+ hardware, software, protocols, and systems overlaps between wildly different applications.
Shouldn’t that be “overlap”? Nope. Look closely. That list of things, two of which are plurals, is the object of “of.” The subject of the sentence is “much”! My compliments to Bruce for getting this sentence right; it would be an easy sentence to get wrong.