BOTH
Money can change your life and the life of those around you. So called friends will suddenly become more prevalent in your life, wanting to be around you more, hoping to catch some fallout for themselves. You can change in ways you never even knew or expected such as when dealing with those new found leechers, errr friends a previously generous man might suddenly become a tightwad, suspicious of all those around me, whereas a thrifty individual might suddenly be more willing to share the wealth than he previously was.
In either case the circumstance can dictate how you act. Does that mean you have changed or exposed the true you? It's hard to quantify since the question could then become: Is this the real you exposed or simply a new version of you, that previously did not exist until the new circumstances existed thereby creating you?
Money can do a lot of strange things to people. It can cause you take risks you never would have dreamed of before, simply because you can now afford to do exciting new things. It can cause additional stress or mental issues where there previously was none. It can cause hobbies or previous fun once in awhile excursions to become addictions, destructive in nature, such as going from visiting your local casino once a year for an anniversary to being there daily, chasing even more money.
The only real you is the you that exists today. Any major change in your life's circumstances may expose previously unknown qualities or may indeed create a "new" you based on a new set of circumstances.