Can I make a living only doing lash extensions?

For context I live in the UK. I’ve been doing lash extensions for about 2 years now and sadly have never been fully booked. I’ve had busy periods, and I do have my regulars, but I would like to earn more. My partner has said I should train in other beauty treatments like eyebrows and lash lifts so that I can offer more services.

Obviously I know that offering more services would of course increase my revenue and bring in more clients. But the thing is, I don’t think I want to do other services? To be honest, spending all the money on training and equipment is not something I want to do right now. On top of that, I’m just lacking motivation and passion. Eyebrows scare me because I’ve seen so many horror stories of grazing and other complications.

I like doing lash extensions. It’s simple, I know what I’m doing, and I think I’m good at it. I’ve never had a complaint, and all my clients love their lashes. I see so many other lash techs that only offer lash extensions, and they are successful. I think my main issue is keeping on top of advertising. I’m really bad at staying active on social media. This is something I’m going to work on.

But I wanted to hear from other lash techs. Do you think it’s sustainable to only offer lash extensions?