The sale should be done if it is mutually beneficial. For example, if the buyer has skills or technology to scale the business up faster than original founder -- then the price might be set in such a way that it would be better for both buyer to buy and for the founder to sell. Another good reason -- if founder is exhausted.

If the reason is just to eliminate risk, then it might make sense to sell part of the business or simply invest part of the profit into something else.