The average worker in the USA makes about $37,000.
The average CEO makes nearly $12,500,000.
$15 an hour is about $31,000 a year, but you have to remember that many hourly workers don't work a full 40 hour work week because they are only given part time hours to avoid benefits, so most people at $15 would actually still only earn less than $25k per year. And that's without paid vacations or paid sick leave, so that figure assumes they work 30 hours every week without taking any time off.
Companies could easily remain profitable if the pay scale were more equitable - in 1980, the average CEO made 42 times what the average worker made. By the 90's, that was 107 times. Today, it's over 330 times more. If CEO pay were still along the lines of 1980's salaries, CEO's would make about $1.3m per year even with the average employee seeing their wages go to $15/hr.
Of course, this is on a large scale, but I am sure you can find lots of companies where the salary scale is skewed significantly towards management at the expense of rank and file talent.
Of course, the people making the salary decisions are also the ones earning the most...