That is a valid point. Most of the people behind the new GTLD program made their fortunes with .COM, most of which they registered 10-20 years ago.
While many of the people involved were successful because of their business acumen and foresight, others seem to have achieved success mainly through fortunate timing.
The people making money now are the ones selling the picks and shovels aka the registries and registrars. They are selling the dream.
It is simply impossible for all these new extensions to hold value. There is not demand in the market to support it. Also, every new extension that comes out will further dilute other new ones. You have similar meanings (photo, pic, photos, photography, etc.), singular and plural, many in a single field (law, legal, attorney, esq, etc.)
The only business model that seems to make sense is unloading as many garbage domains as possible either for free or sub $1 regs (XYZ, TOP, etc.) and hope a small % renew their domains.
These extensions are the reason the total gTLD registration volume is a joke, as well as many hundreds of thousands of registry reserved domains.
Brad