Perhaps:
bitcoin?
There are very few of me to see. If there were none, there might (not) be glee.
The fact that these are limited & hard to find is their value. At the same time, many in the establishment would be happier if the technology weren't known.
Easy, 1 thing to rid of me. I can come and go fast, to those readily!
Easy to get rid of (spend). Also, transactions are cleared very quickly.
You might not notice, look carefully. As you look over my family!
Most people haven't looked into bitcoin in any detail. And, it may not be bitcoin but the family of currencies based on block-chain technology? IE, the algorithms.
You may end up changing what I might be, As you influence us pretentiously!
Money has potential to purchase (ie change into) almost any thing. Also, money tends to breed pretentiousness. At the same time, the technology is somewhat undeveloped & it may not end up being used for currency. It may be used for something else. There is also some hubris to the bitcoin aspiration to compete with / replace national currencies.
But, to be honest this last clue keeps me coming back to something that is
biological in nature & too-often mutilated by humans to their own ends -- such as a virus or a morel.
Maybe I am close at least? :) Fun puzzle!