So go ahead and take that $5,000 signing bonus to drive a chemical truck, if you are so inclined. Just don't spend it -- except maybe on classes to learn how to do something other than drive a chemical truck.
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Problem with the "sign on bonus" as well "retention bonus" and "safety bonus" is that they are doled out over a specified timeline so "saving any for another use" is nearly impossible unless one has nearly ZERO living expenses.
There are countless ONLINE CLASSES to learn about MANY POTENTIALITIES of working ONLINE as, say, from home, with no commute, which might not interest some Truckers.