I'm someone who loves mining and have worked in it before. However, mining is currently expensive and requires a large capital investment, in addition to the cost of electricity and maintenance. Therefore, if you have a large capital, it's a good idea to mine now and hold Bitcoins in the long term to reap greater returns.
Therefore, for those who can afford the costs of mining, combining the two methods would be great. For those who can't afford the costs of mining, investing is better.