Unless you love computers I don't think anyone who hasn't made a decent living as a face to face trainer can expect to do it online without spending a lot of time learning business skills as well as training and nutrition skills.
However, if you set up great systems the potential income you can earn online compared to face is through the roof.
As you grow it is also seriously easy to get great people to work with you online compared to coming in to your facility or training clients for you in a face to face environment.
If you want to live a semi stress free life and earn 50K a year, face to face training can be amazing. You can get there by simply walking the gym floor and being a great trainer.
If you have ambitions for more and want to have a life while doing it then online provides an incredible option. A simple online challenge, flagship product and post flagship membership can easily earn you more profit than running a successful training studio with 5-10 employees and all the stress that comes with it.
However, you need to build a global following, learn how to set up systems and really know how to target your market and show the world what you have to offer. You don't have the option online of starting a studio on a popular high street and getting 2/3rds of your new business from walk ins... That said it won't cost you any where near as much to start up as that studio would!
What happens when you're 70?!
In the future you can continue to earn money online for as long as you wish to, your business will also become a very valuable asset should you wish to retire. Face to face can be much tougher, I don't know of many people who want to be personal trainers in their 70's and this will be a reality for many as the pension age continues to rise and trainers don't invest outside of paying for life.
Lets face it, the competition online is always likely to be strong, the cream rises to the top and you are competing against the best in the world. However, the potential market is much, much, much larger and you only need some of them to think you are the best option to do really well.
This is why things like building a following, having a specific niche and showing your personality are so important online.
The competition online can be intimidating. It's easy to think you are competing with the Gillian Michaels, Tracy Andersons or Joe Wicks of the world along with the big budgets and publicity machines that go with them. If you offer cookie cutter training programs and meal plans, show no personality and don't have any form of niche other than fat loss then you probably will be and you will likely go nowhere.
However, a quick shift to an niche that you know and love, an ease with putting a camera phone in your face and talking an a way that potential clients resonate with and connect with and those guys will no longer be your competition any more than Mind Body is not competition for PT Distinction.
The details of this are for another article but if you can find a subject you love and enjoy being obsessed with then talk about it in a way that nobody else does (I.e. your way) then you will never need to be too concerned about the competition, you will just need to stay obsessed, stay consist and and keep being you.
Face to face
Face to face the competition is really limited to who is in your local town- other trainers, gyms and slimming clubs. The size of your town/ city and the quality of your competition will determine whether you even need a niche at all.
In summary if you have a specific passion and a specific type of client you want to work with then online is better for you as the audience can be much larger. If you like working with lots of different people and your ideal niche is simply being the best in your town then face to face is a winner, though running a hybrid model of face to face with added online coaching would probably help you dominate further.