I would like to contribute to this topic from two ends. Wealth has a habit and poverty as well has a habit. Wealth and poverty starts from the mind. You can't actually make true judgement on a person's character until they've been tested either by extreme situations of life or power and wealth.
Source
Mask off.
There is this change that happens when people are given power. Money is also a form of power. This new person that they have "become" has always been there, you just got to see the version of them with money. If you pay attention closely and are observant, most times you would always see traces even in their humble stages. The mindset of a person is what forms their character, power only comes to expose the mindset that didn't find expression initially because it was limited by resources. A kind person will always be kind and a Giver will always be a giver.
Change is a necessity.
To be Sincere, most times, people are often biased. As one transitions, change should be expected. After so much struggle and sacrifice to make wealth, imagine being surrounded with people who only see you as a leverage. Some people think that by virtue of just knowing you, you should always be there to attend to their needs even if these people were not really there for you at the beginning.
One thing that is harder than getting money is sustaining that money. To sustain wealth, it is only wise that you surround yourself with productive thinkers. This doesn't mean you should avoid well meaning and visionary friends you had from the beginning. Having people who always come to take, with some sense of entitlement and never looking for a way to support in anyway is a parasitic environment. And when you take decisions to avoid such, people would always categorize it as pride or you've changed.
While Change is a constant of Life, with money or not, one's character is independent.