If a 30  year old Electrical Engineer wants to make more money per year should he also get a degree in Accounting and Finance to work?

Nobody with a EE degree from a University in the US would ask a question that stupid.  So since you are not a EE, what possible reason to you have to care.?

That takes too much time. Drive a cab instead.

Or look for a better paying job.

There are several ways to make more money.

I knew a fellow (I took his class) who at night taught accounting for engineers at a state uni. I suppose he had at least a Bachelor's in Accounting, but given that it was a very reputable uni, probably at least a Master's, perhaps even a Doctorate. His day job was engineer (I can't remember what kind).

Most engineers I've known make extra money developing an idea or service at home and selling it to others (usually: other engineers or specialists who need the product or service). That's especially easy nowadays with the WWW.

For example: I knew a biomedical engineer who made pH "probes" for swallowing (as opposed to nasal insertion). He personally had found it less trying for the patients, and he discovered several doctors and technicians who felt the same way.

I knew another who acquired expertise as a roller coaster tester. He would ride newly-built roller coasters with a little device he designed that would record the forces a rider experienced on the coaster, and so he could "certify" the coaster as safe to ride (if the forces were never so great as to be a danger to the riders).

There are engineers who have become famous authors.

etc.

The sky's the limit.

What moves you? What do you most want to do other than engineering (occupation-wise)?

Whatever it is, become an accredited expert.

If engineering is your one, true love, then start a fly-by-night business doing something that requires engineering. Specialize in an area that moves you.

Or, perhaps the most obvious solution: acquire a doctorate in electrical engineering from a well-respected uni.

Anything is doable, become a licensed CPA and the sky is the limit.

You can't be good at both so pick ONE kid