I believe that is an egregious oversimplification. Now, I'll caveat what I'm about to say with the statement that I traditionally recommend that people buy a driver rather than a restoration project, simply because it's a heck of a lot easier for the average enthusiast.
Restorations are a factor of Time, Money and Skills. Not since my first restoration purchase have I ever lost money on one of my projects. The difficulty in this is being aware of what you're getting yourself in to, and that knowledge only comes from experience. So the average first timer gets themselves in *way* over their head.
<span style="font-weight: bold">Main factors:</span>
#1. Look over the car with a fine toothed comb. Bring someone smarter than you along for the ride and listen to them. Don't be afraid to be a pain in the ass.
#2. Understand that your skills are likely lacking, and honestly assess what you can and cannot do.
#3. Understand, based on #2 where your costs will be.
#4. Understand how much time you can realistically spend on the project, and what your rolling budget is.
<span style="font-weight: bold">Cost Breakdowns:</span>
#1. Cost of acquisition - how much is the vehicle.
#2. Cost of outside service - how much you're going to need to pay someone else. (for most folks this is a minimum of Machining, Body and Paint)
#3. Cost of parts - Assume that every consumable has to be replaced & the engine will be rebuilt.
#4. Cost of tools - This catches many by suprise.
If the sum of the 4 is greater than the cost of a driver, then the purchase doesn't necessarily make sense, unless that's the only way you'll ever afford the vehicle.
If doing this didn't make sense, I'd never have purchased a vintage car.