If one uses money wisely, caring for others and donating to worthy causes, it certainly is not a sin to be wealthy. However, when one uses money for the harm and detriment others, that for sure is a sin. Selling illegal drugs would be an example of this.
1 Timothy 6:9-11New Living Translation (NLT)
9 But people who long to be rich fall into temptation and are trapped by many foolish and harmful desires that plunge them into ruin and destruction. 10 For the love of money is the root of all kinds of evil. And some people, craving money, have wandered from the true faith and pierced themselves with many sorrows.
Paul’s Final Instructions
11 But you, Timothy, are a man of God; so run from all these evil things. Pursue righteousness and a godly life, along with faith, love, perseverance, and gentleness.