So, it appears now that not "everyone on the internet says to not invest in ngtlds"?
Now when you escaped from the matrix, it is time for research.
Check Namepros threads, namebio.com, sold.domains, dnjournal.com for reported ngtld sales. Become a member of ngtld forum - you can easily find the link - and read it in a whole.
Carefully analyze reported sales and try to register few similar names. If you have no large enough cashflow, don't register very expensive premium domains. Nowadays most of ngtlds are available, for the first year, at the registration cost of .com or less , and there are many nice names still unregistered.
You need clear business plan. Don't rely on possible ngtld sales to pay off renewals, until you finally realize what names will sell.
Take any advise with grain of salt. Follow the numbers. Get ngtld zone files and check what extensions got many end user registrations, what extensions got many developed websites already.
Follow all famous domain forums/blogs/media regarding ngtlds. Try to focus on not what people think of ngtlds but rather on facts they report. Sometimes going through lengthy discussions you will find only a small bit of useful info - but that info can help a lot.
In other words, do what all domainers must do if they want their domain business to be profitable in any niche: thorough research. Replace "ngtld" with "gtld" or "cctld" to be profitable with them.