The only reason for this imo is due to loneliness.A guru who is a retired teacher and simply enjoys teaching, but has achieved real success in trading since retirement and takes genuine pleasure in sharing knowledge and improving noobs' skill sets.......
If said teacher needs people, then get a wife or girlfriend/partner, that'll cure the person.
Teaching strangers is like advertising to sell stuff on 'Buy, Sell&Exchange' web site.
Lots of rubber neckers turning up, banging on door all hours of the day and night, parking on front lawn, running over plants, breaking retic, eyeing up house so come back to burgle, haggle down price then complain, bad mouth you to all and sundry. Yup, way to go.
