Grow it or expand?

I am in a position that I would like to build my business further as I feel that not much more I can do working on my own, however I’m not a big fun of emptying someone at the moment as I like that I can ensure best quality of my job. If I’ll have someone working for me it will be very difficult to have the assurance of quality, so it is on my mind. Should I diversify with so.e new business that could be run without me being a main value adding individual or just employ someone that I can increase volume of what I am doing and by this gain some more experience.
There are things on my mind that I would like to start, one of them is to start selling things online, like supplements and other things related to sport and fitness.

I know that starting business based online I can certainly have economy of scale and by this increase my potential return on investment so that I’ll get quicker to were I want to be. As I do fancy getting my first million before I’ll turn 40, so fur getting there slowly (way to slow ?)