Depending on the specific dancing style there are strict body types and features that you need to have, and not all of them can be acquired by training. So yeah, nature is not fair but feel-good comedies don't always apply to real life.
Others have pointed to you that to dance you only need to be able to move, to that I agree. But between dancing and have a profession out of dancing there's a big difference.
There are lots of reason why now I can't base my income in dancing, I'm telling them as to give a data point as to why it's not allways as easy as "if you want you can".
First: I don't live alone anymore. Married with some obligations. My income needs have grown, even though there are two sources of income.
Second: Physical activities require discipline, that I lack, and time, which is now spent on my "new" job, my partner and housework.
Third: There are several possible incomes for dancing. None of them make the cut as a great source of income. * Payed exhibition dancing is usually done by younger and more talented people, also it's inconsistent income. Done a bit, enough not to find it feasible. * Competitions don't pay that much, lots of politics in there. * Teaching (which is what I love) doesn't pay much unless you have a name, with low salary you'd need lots of classes, but names teachers get most of them. * Staff work pays less than teaching, necessary for the school to function, but boring.
Fourth: compatible schedules. Being with someone that lives in "the real world" means that working 15 to 23/24 is not seeing them (staff+classes+parties). That and money where the primary causes for my change of career. Priorities matter.
Fifth: People tend to prefer tall, fit, young, handsome male dancers and short, fit, young, beatiful female dancers. Each point where you diverge it's a handicap, I have several.
So yes, I could have kept on my dream job, but I would have to leave behind too many things that I need, like my SO, and would have to go back to living with flatmates. All that, in my early 40's, is not what I want of my life.
"Never stop dreaming!", "if you believe you can do it" are nice phrases to throw at people, but you can cause them to lose their grounding in reality, where sometimes dreams have to be crushed for the greatest good.
I never said it was easy. Unfortunately, this is not a perfect world, and most of the time you have to make sacrifices in order to do what you love. In your case, it means lowering your living standards, but that's up to you, I respect that.
At least that one doesn't not seem to imply dreaming about the same exact thing forever. In other words it might be something else if dancing didn't work out. Still seems to me (I'm in my 30s) that someone with a dream can definitely get further compared to someone with "bullet points" so to speak.
If you have all your limbs and can walk, you can perfectly dance whatever is that you want. If you're fat and can't dance no more that one minute without getting out of breath, get in shape and train endurance. As simple as that.
If you're 5.4" or less and feel intimidated dancing with a taller woman, find yourself a woman of your same height.
You shouldn't be cutting away wings and locking up birds in cages telling them they can't fly.
Mental handicap imposed by oneself -or others, which at the end of the day ends being oneself- is the worst of all.
If you think that all it takes for dancing is "not getting out of breath" then I can see why you would think "anyone can do it"
Although even with modern, there is a strong school aiming to democratize dance. My family were performers in Kaeja D'Dance (http://www.kaeja.org/) Porch View Dances this year (look it up if you like dance) and the performances were very good. The choreographers were very careful to work around body types and capabilities.