Psychologically we are tied to NEEDING results from our actions
If we learn something we expect to KNOW it
If we give tzedakkah, we expect the Oni to be better off for it.
L'havdil -The Greeks have a myth of Sisyphus in which he is condemned to roll a boulder up a hill, but to no avail as it will roll down again.
The Torah in many ways is not so concerned about "results", provided one has given it his/her best shot.
Thus, "Why bother?" Is no excuse not to learn Torah because one will never finish [See Avos de R. Nattan 27:3, also sefer Chosen Yehoshua]
Also - "Lo alecha ham'lacha ligmor, v'lo ata ben horin l'hipateir mimena"
Same thing with Mastering laws of Lashon Hara. [The Choffetz Chaim Lesson a Day p. 59 - which is also the source for quote above from ADRN]
I claim the same point with regard to Hochachah. We cannot give ourselves a "Why Bother" heter to avoid a d'oraitto! Logic is not an excuse to avoid an obligation. After all, we could easily rationalize away a number of Mitzvot.
The Talmud requires Hochacha "afilu mei'ah p'amim". I would be happy with even just ONE sincere effort before giving up, regardless of the prospects of success.