It could also be a result of a hidden "Zero-Sum Game" belief relating to wealth and happiness.
I wrote an article about it yesterday. For anyone who wants to read the full thing it's here:
Get Rid of Your Zero-Sum World View and Shed the Guilt | How to Make Money Doing What You Love .
The basic premise, however is that a lot of us have a zero-sum mentality/belief/world-view which subconsciously tells us that by having something you are taking that thing away from someone else.
Meaning, if you build your wealth by $50,000, it means that someone else out there is now $50,000 poorer because of that, which makes you feel guilty.
It's a pretty crazy and unlogical theory, but it's installed in the heads of almost all the people I know (that are also poor) and used to be a belief that was holding me back too.
The crazy thing is that it doesn't just relate to money either. We are conditioned to believe that by us being happy, we are somehow taking away happiness from someone else, which is absolutely REDICULOUS but that doesn't make it any less common.