That's terribly easy to get around. The rich don't operate as sole proprietorships. Instead, it's a family business with money held in trusts and word of mouth

That's terribly easy to get around. The rich don't operate as sole proprietorships. Instead, it's a family business with money held in trusts and word of mouth contracts. "Falling out of favor with the family" is a euphemism for violating some form of an agreement. And when you hold public office, there are plenty options to deal with dissenters. Placing restrictions on what investments a person holding public office can hold is a very naive solution. Instead, acting on material nonpublic information is what should be against the law.