That's very doubtful.
Actually they were the poorest of the lot. Loyal to what?Thousands of new immigrants to the country turned out to be more loyal patriotic Americans than the disloyal native-born secessionists.
Plenty of evidence they did it for Financial Reasons. Bounties had to be raised to the point they would enlist. If they did it for the Cause, why did they charge so much?
So your analysis is a Myth