Take it from me, I registered GTLD's since day 1, to protect some of my .com's, which 5 years later I didn't need to do. When the G's first came out inquiries were coming thru, marketing dollars were being spent, there was buzz, confusion, and a sense of excitement among newbies of a second gold rush possibly.
Fast forward 5 years, the inquiries are way down, I am lucky to have sold some of my stronger ones, early on setting records in several extensions, but the people looking for these mainly only have $100 or less budgets, and no real business plan, more hobby, or side business kind of thing. There are still deals getting done in 4 figures, it is the luck of the draw, or premium renewal names, or registry reserved which are garnering the attention. If you have the good names without premium, probably means you paid 4 figures in EAP to secure them, with a renewal 4X .com in most cases, it makes the investment grade consensus very hard to balance out.
If you check out that other forum GTLD extension LINK, it is a ghost town, if you go back, and read how excited people were 5 years ago, you will see some of those people really bet the farm, and took a huge losses. I have never heard LOLWARRIOR talk of any sales?
There will always be people who can carve out a niche in any crappy little industry, but most people want to be where the action, and the dollars are, and that is .com. You don't have to upsell, or BS it, when it comes top level it is what it is. These people write these BS articles, are not in the trenches everyday seeing the inquiries, and from who, seeing the new products, and who comes knocking to secure their brands. The domainers have the first insight to what is moving, and what is not, don't let anyone fool you, stick to your gut. Why work harder than you need to in crappy extensions. To be honest if .biz, or .us were released in the early rounds in 2014 do you know how much money they could have extracted early on, but we already have the data on them, nobody wants them, premium one word .biz go for 3 figures, why do people keep arguing without any real sales to back up the not so obvious.
There will be another round of GTLD's in a few years, not because they are needed, but simply more money can be extracted from companies, and consumers based on fears of brand protection, and hype of a new gold rush.
The whole purpose of the GTLD's were that there were not enough good .com's available to register, or they were to expensive on the secondary markets. What happend registry reserves, premium renewals, warehousing, and in most cases the annual renewal on some gtld's is the entire cost of an aged .com in the aftermarket which only carries forward with an $8 renewal, and not a 4 figure renewal renewal on an annual basis. It is an utter nightmare, as you have so many operators running so many different ways, all with a different set of rules. There is no protections in the framework for consumers when it comes to GTLD's, an unruly operator could easily extract a keyword extension from an owner by raising the price to a million dollars a year, since there is no cap, or no framework in the contract to directly contact the registrant, simply the registrar.