I am UK national applying for a PhD (microbiology) in the USA. The application process requires a statement of purpose which includes, among other things, a section on recent / current work activities that are relevant to the application.
I am a Master's student and have plenty of relevant details to talk about from an academic perspective (there is a separate section for this), but I also run a successful IT business and the transferable skills that I have learned from this form a core part of my relevant work experience for this section.
To illustrate my motivation and potential for success at graduate level, I was going to mention that I essentially started my business from scratch a few years ago and now earn a six-figure income. However, I am worried that the selection committee might view this unfavorably (talking about income is quite a taboo subject here in the UK), or worse they might question my commitment to a graduate program if they think I have a comfortable job to fall back on.
I should also mention that the PhD program I am applying to is fully-funded, but the cost of living in the area is notoriously high and most grad students have to supplement their income by teaching. I wouldn't need to do this as I have enough savings to be financially secure for the duration of the program.
Should I mention my income to demonstrate my aptitude, or will it do more harm than good?