Do long trail keywords really work?

I had created many websites and read about different techniques to do proper SEO.

But I'm confused about long trail keywords.

Like if a good authority website is ranking for "nike shoes" then it is the waste of time to use long trail keyword like "best nike shoes for running on a treadmill".

If someone types "best nike shoes for running on a treadmill", the authority sites will pop at the top.

No matter how much SEO, the result will be same (authority sites will rank better).

So what's the point of using long trail keywords???

That may be true for this specific case because the keyword you used in your example is a keyword used by people with a search intent of buying stuff (that group of search intent's keywords is also called "commercial investigation", as they are searched when you already have the idea of buying something), so even if it's a long-tail keyword you can be outranked by very big sites in that niche.

Long tail keywords work better in an informational area, for example you have the largest seed keyword "programming" and as a long tail keyword you address a very specific problem or question that can arise: probably nobody answered that very specific question, and here you can write an article and rank a lot easier with your post.
That's because if you need a specific solution you don't need a generic introduction to programming, even if it was written by a huge coding website, because that would be useless.
Even better if you make your post as a answer and you can also manage to answer that question suggesting an affiliate product, in that case you hit the jackpot, but it's not something you can always do, sometimes you simply get to have more visits and just build topical authority for your website, and that's indeed not useless too.

its all depend on content and backlinks

Since long tail keywords only consist of a few words, they are much more specific, meaning that both users and site owners receive better results.

long trail keyword do work but is all depend on the quality of your content and competition.