最近、word-reference forum の"English Only"と言うところに投稿をしています。その内の、まあ、役に立つだろうと言うものを、こちらにも掲示しておきます。(英文の内容は結構いいはずですが、文法自身は多少間違いがあるかも知れません）
I assume the word 'much' carries connotations of dynamism, chageableness and feasibity to accept influence from others.
This is simply because 'much' means something abstract, something you can not see or touch.
These connotations, I think, fit in with negative/interrogative sentences as well as sentences such as "I have too much money." and "I have as much money as him."
The phrase 'a lot of" carries connotations of concreteness, unchageability and solidness because 'lot' is a noun which means a unit you can touch or see. These connotations fit in when you want to stress the largeness of number or quantity.
1. "Many people want to go there."
2. "Much money has been spent on that project."
Those are idiomatic.
On the other hand,
3. "He has much money."
is not idiomatic.
The difference between those is the locations of 'much', the subject or the object.
Subjects are the things which indicate things that exist in the world as they are. They do not get affected by the verbs. They are the things which affect the objects.
Objects are to be affected by the verbs.
In the sentence, "I have much money.",
1. A collision happens between the verb and 'much'.because they are put togather side by side.
2. "Much" easily yield to the pressure by the verb and can not retain its meaning.
3. This is the reason people do not think this sentence is idiomatic.
4. If 'much' is not placed just after the verb, it's not affected by the verb, and retains its meaning.
5. This is the reason "He has too much money.", "He has as much money as her." are idiomatic.
As for "I have much money saved for a rainy day.",
the 'have' does not play the main role in this sentence, it's 'saved' that plays the main role. So, the collision is not so hard.
I'm not sure if "He has, I imagine, much money." is idiomatic or not. Could you give me a comment on this?