You know what happens after you finish with your schooling?
You become the teacher.
The question then becomes, What are you teaching?
We are all teachers
Everyone you encounter is a student in that they learn from you.
Whether they learn something positive and helpful or they learn negativity and frustration is completely up to you.
Your actions are your lesson plans
You can set a good example and teach something worth learning by being productive and positive — or you can bring more negativity in the world by putting your bad attitude and pessimism on display for others to emulate.
What are you teaching?
And would your students give you a passing grade?