Actually, I would tend to see it the other way around. The rich man would not be rich for long because he would respond to Jesus' teachings about "where your treasure is, there will your heart be also" and "sell what you have give it to the poor, and then you will have treasure in heaven".
Why would anyone want to continue being rich after reading something like that?
They may continue to work in a high paid job so they can give more aid to their church or those in missionary work
So now we get to the real nitty gritty eh?
have a look at this;
Mat 6:24 No man can serve two masters: for either he will hate the one, and love the other; or else he will hold to the one, and despise the other. Ye cannot serve God and mammon.
I believe this teaching is appropriately applied to your comment about witnessing at work. It is from the sermon on the mount and addressed to the followers of Jesus in general. You see, witnessing IS our work! Any time we spend working to get more money is time we spend showing our contempt for what God wants us to do, and any time we spend working for God is time we spend showing contempt for the values of this system.
This isn't a teaching for some people. It's a direct challenge to the love of money right at it's core.
I have addressed thios above. If a person works and earns good money and uses the surplus to their needs for God's work, is this wrong?
Luk 14:33 So likewise, whosoever he be of you that forsaketh not all that he hath, he cannot be my disciple.
This teaching is also addressed to the followers of Jesus in general. See where he says "whosoever"? That's fairly inclusive, I think.
But what is the work God would have an individual do? It is different for all. Did Paul peter, James and John tell all the people in the churches they wrote to to abandon their jobs? No. Paul admonished many to get working and earn their living
How about this one!
This is Peter, declaring that they have forsaken all to follow Jesus. The reason he is saying it is because Jesus just told a rich man to forsake all, and the rich man didn't want to. And THAT was in answer to what the rich man must do to have eternal life. Think about it. God is no fool. He is not going to fulfill a promise of the magnitude that eternal life represents if we are cheating on the rules.
The reward is eternal life. The price is everything you cling to. What's it gonna be? It's almost like Peter was kind of breathing a sigh of relief when he made the comment above. How hard it is for the rich to get into heaven. They just won't let go of what they cling to!