All in all I find myself in agreement with the following exceptions or observation.
Project guns can be a good thing if brought with a true vision of the cost and value when complete.  When I had 38 long guns you are more right about it than I care to admit.  However, when I am reduced down to four guns plus one or two projects are valid. (I cannot decide if one of my double rifles is a project or simply a gun sale not yet made)
My rules for project guns are simple.
1.	 Understand you will be upside down when complete.  This is a 95% probability.
2.	 The gun has to fit an actual need other than desire.  I.E. You need one heavy waterfowl/clays SxS in your battery and this will be the only one you will own.
3.	 You pay cash for all work, no debts for either purchase or restoration
4.	 I look upon all gun ownership as rental ownership.  I have made actual profit money on a gun deal a few times out over 50.  All profits, the few I made, were made on the purchase price, not the sales price.  They did not go up in actual value.
5.	Never have more than one project gun at a time
These rules stated, I admit I did not always live by them until the last few years.  I own one completed project gun and recently purchased a new project (matching 20 SLE to a 12 & 16 on hand).  My pleasure from six SxS guns is greater now than when I had 38. 
Lastly in respect from your comments in having too many hobbies, I cannot more agree.