Most things... things that are for sale, the profitable stuff... they're designed with people in mind who have what you might describe as a passing, or casual interest in that thing.
The people who are really passionate and into something for the long haul, they become deeply invested in it and... I want to say they gravitate towards "quality" but that's not always the case. They gravitate away from the mainstream though, at least.
That's not to appear snobbish either. It is entirely OK that not everyone is into fine art, for example. It's ok if you prefer a rom com or an action & CGI blockbuster over foreign arthouse films.
One thing is for sure though... when the Spice Girls came out circa 1994 singing "I really really really want to zig-a-zig ah" and became the biggest selling female act of the day... it wasn't because that was actually a genius piece of musical and lyrical composition that people with a real passion for music felt a deep emotional connection to.
God... 1994... what a shit year. Maiden didn't even have an album out at all, rendering the entire year a complete waste of time IMO. In hindsight and if it was possible, I'd have just skipped the whole thing until The X-Factor was ready for release.
But anyway I digress. People with a casual interest in commercially produced music as entertainment ate that stuff up and people got rich. All good. Supply and demand, capitalism, all that stuff.
The fitness and fad diet industries work the same way. And like I said... fad diets are often harmful but at least as far as the exercise stuff goes, that's fine. I realise that now, as a more mature aged adult. It's fine if people just have a casual interest and think "hey that might be a bit of fun, let's go give it a try"... it's safe to use Zumba as an example by now without offending anyone, I hope?
What you have to realise though is that if you're really looking for more than just "physical entertainment", when you're really looking for lasting & ongoing results and to achieve something... you have to consider the difference between stuff that is designed to be sale-able to people with a passing / casual interest in exercise, and a serious & strategic approach to training for someone who is passionate and in it for the long haul as a defining aspect of their self-identity.
Now... even if you don't (yet) identify as one of those people who are super-passionate about training, you want to emulate the sort of approach that such a person is likely to have, to the best of your present ability. The passion for it will come in time, as you reap the rewards of productive training in terms of your physical health and condition, and how you feel about yourself and your ability to achieve and succeed when you set your mind to it.
So... a lot of words here but to sum up: the difference between stuff that's designed to be marketable to as many people as possible with a casual or temporary interest, vs stuff that's made for people who are looking for something to really become invested in, identify with and become passionate about. It is well worth understanding the difference, especially if the latter is what you require.