I don't get car poeple at times ?

Please don't take this the wrong way but?

I don't get why some cars have lots of money in them but not yet finished and told it's not worth the money it has to be sold cheap.
But yet some guy buys a 1000 to 1500$ rust bucket and in the long run spends more time and money just on the rust alone, then it would have took to buy the car almost finished at the price that's been invested in.

Well...aside from the accomplishment factor, aside from the immediate reward of viewing ones handywork a piece at a time all the way to fully restored and assembled, not to mention the love of the hobby. there is no reason. It has been said hundreds of times and repeated over & over...if you are in this for the money you are in it for the wrong reason and will certainly be disappointed at some point. Even the cars at BJ's & Meacums are often auctioned for a relative loss compared to what it took to build them.... if you were to REALLY total up everything and I mean everything from postage to electricity to light the area you work in.....along with your labor.... ALL of it, researching on the internet, searching for parts, phone calls PMs etc etc and attach an hourly rate to that there is a small fortune invested in each & every one of these vehicles.....the "rarer" or more scarce the vehicle the more the cost.....and Mopar typically had the smallest build & sold numbers of all the big 3...... to your point these people are generally NOT in it for the profit or the "buy driving" they are in it to re-create, to feel the satisfaction of their ability and for the love....
Financially speaking these things are often worth more as parts than fully assembled vehicles.... interestingly enough so are the new cars...the sum of the parts far exceeds the cost of the vehicle.....