Assuming:
(1) the average minimum wage over 27 years is about $10/hr
(2) he works full time and takes a little time off each year for holiday/vacation so that he averages 2000 hours per year
Then the math is:
2000 hours per year x 10 per hour = 20,000 year gross, probably 17,000/yr after taxes and other deductions.
$17,000/yr x 27 years = $459,000.
But who can pay for housing, food, clothing, utilities, medical care, and just plain old expenses on $17k a year? He probably had very little saved up at the end.
If someone is so dedicated to a job that he stays 27 years, never misses a day, and does a good job and makes his boss happy, then I would certainly kick in a few bucks to a Gofundme to buy that man a house!