Of course, these results are correlational, and so it’s not clear what’s causing what. It could be the case that the spending habits of spendthrifts are most sensitive to changes in income. In economic terms, the marginal propensity to consume” may be greater among spendthrifts than among tightwads. Alternatively, it could be the case that spendthrifts who particularly enjoy to spend are particularly motivated to seek high-paying careers that can finance those desires. That is, income is not randomly assigned, and different consumer types may select into high-paying careers for different reasons.To summarize: people choose to obtain jobs that pay high salaries so that they spend money, and people choose low-paying jobs if they don't like to spend money.
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This is only a summary of the analyses conducted thus far, and there is more to do, but the initial results argue against the differential marginal propensity to consume hypothesis. Instead, the results provide some initial support for the selection hypothesis, namely that different consumer types select into high-paying jobs or careers for different reasons.
To quote my co-worker, "I guess conversely, people who don’t like money really enjoy being poor. Sounds perfectly reasonable to me."