85% of people who get a concussion will spontaneously recover to a condition where they are symptoms free and can return to their prior activities. This does not mean they have achieved a full recovery. They will be subject to relapses when they stress their brain either physically (trauma), emotionally, with illness/fever, or with poor nutrition or ingestion of detrimental substances (drugs, alcohol, caffeine, MSG, etc.).

The 15% who suffer Post Concussion Syndrome have a wide range of recovery experiences.

Everybody will improve if they take proper steps to help their brains heal. The most important step is to get quiet rest and avoid anxiety, especially anxiety about when they will get better.

An important consideration is past concussion and sub-concussive impact history. Those who suffer concussion playing sports often have a prior history of concussions that went undiagnosed and sub-concussive impacts that were entirely ignored. The cumulative effect of prior concussions and sub-concussive impacts can make a big difference in recovery speed and level.

Yes, hope is important but it is meaningless if the concussed person does not take steps to aid their own recovery. Waiting for that expected recovery without considering changes to life habits and activities will end in frustration.

Once concussed, always concussed. Learn to minimize symptoms when you can. Learn to accept and work around those symptoms that seem to be persisting. And, make changes to avoid that inevitable next head impact. We all will suffer another head impact even when we try to reduce the risk. Taking part in activities that are known risks such as collision sports is sure to chip away at our ability to live a full life.

There are a few of us here who personally understand the cumulative nature of head impacts. Most of us stopped the risky activities long ago but still suffered accidental head impacts during no-risk activities.

As the axiom goes:

A fool does not learn from their own mistakes.
A smart person learns from their own mistakes.
A wise person learns from others mistakes.