@Joseph,
Sure the punishments are out there, but is that why you shouldn’t do the aveiros? These “fire and brimstone” warnings, are usually reserved for people who are doing Aveiros, knowingly, because they couldn’t care about their relationship with the Aibershter, and aren’t really interested in what he wants.
Tell me Joseph, if Gehinnom were to close down (due to “lack of interest”) would you still be a frum Yid? What if Schar also stopped? Why would you continue being frum?
A practical example:
Until 20 years we aren’t punished for our Aveiros, so why shouldn’t one do Aveiros until he or she turns 20?