Many of us in science and engineering may use Lie groups without realizing it.
I came across the subject about 30 years ago during my earliest years at university, and had planned to pursue study of Lie groups and algebras, but I got distracted and went in another direction. Abstract algebra was never an big interest - but then perhaps if someone had shown me soon enough, I might have gotten interested.
I had also wanted to study nonlinear mathematics, but at the time I had the interest and energy, there were no courses.