His numbers seem a bit off & inflated to make the point.
For example - why does he have to buy 3 domains per idea he thinks up? Getting the .com alone would be sufficient until he actually does have a prototype. Similarly, why is he bound to hold on to them for 3 years a piece?
A good alternative would be the "1 year rule" or buy a domain & commit to not renewing if you don't have a prototype finished by the first year.
All of a sudden - instead of risking $40k, you've got that by a factor of 10 (and that's if you're actually buying a domain every single day). At that point - the domain buying either needs to be a part-time job or is a really bad exercise in procrastination & distraction.
Alternative Numbers
> 1 Year - 365 Ideas
> Domain - $10.50
> 1 Year = $3,650