The reason why people believe spiritual leaders should not engage in activities like trading and gambling is because it may raise concern among the members of the church and as well might distract the pastor from their heavenly duties. We all know the attention/commitment that trading and gambling need to be successful. A pastor cannot give the same attention he gives the church in terms of support, guidance, and spiritual satisfaction to gambling/trading.

There is nothing wrong with doing something else aside from being a spiritual leader. There are businesses, investments, and other activities they can engage in that won't distract them from their Godly duties.