Can a person be insanely rich and a good Muslim at the same time? The Companions of the Prophet Muhammad (saw) didn't think so.
Ali bin Abi Talib (ra) says: "4,000 dinars is necessary for life. Anything above this is hoarded goods."* By 'hoarded goods' he meant the term mentioned in the following verse:
وَالَّذِينَ يَكْنِزُونَ الذَّهَبَ وَالْفِضَّةَ وَلَا يُنْفِقُونَهَا فِي سَبِيلِ اللَّهِ فَبَشِّرْهُمْ بِعَذَابٍ أَلِيمٍ
"Announce painful torment to those who hoard gold and silver and do not spend them for God's sake." [Holy Quran, 9:34]
We can use Salman Al-Farsi's (ra) way of life to translate the 4,000 dinars into today's currency. Salman was a close friend of Ali and they shared similar religious views. He used to store in his house enough provisions to last his family a year. He would give away everything else he made.*
It is your right to have a comfortable life. And saving money is allowed in Islam. But there is a limit as Ali bin Abi Talib said.
If you have everything you need, and your budget for a year is $20,000, you can keep the 20,000. But anything above this will go into the category of 'hoarded goods'. You should give it away, or start a charity organization with it.
*As mentioned in Wi3adh As-Salateen (وعاظ السلاطين) by Dr. Ali Al-Wardi.
More on QuranClub about money: Illusory Grandeur and Ungratefulness - Objects of worship