There are several reasons why you might consider a firm mattress:

Better Support: 

A firm mattress can provide better support for your body while you sleep. It can help to keep your spine in a neutral position, which can reduce the risk of developing back pain.

Alleviate Pain: If you suffer from back pain, a firm mattress may be a good option for you. A firmer sleeping surface can help to alleviate pressure points and reduce pain.

Good for Stomach and Back Sleepers: If you tend to sleep on your stomach or back, a firm mattress can provide the support you need to keep your spine aligned properly.

If you prefer a softer sleeping surface, a firm mattress may not be the best option for you. Ultimately, the best mattress for you will depend on your personal preferences and needs. It is always a good idea to try out a mattress before you buy it, to make sure it is the right fit for you.