The Netziv says (footnote) that Avraham Avinu’s specialty was mainly in learning Torah (and he has loads of Chazal’s proving it. He says that Yitzchok was Tefila, and Yaakov was Chesed!) So why do we find Avraham Avinu being the Baal Chesed wherever you turn? First of all, they say that his main Chesed was in Ruchaniyus, as it says: וְאֶת הַנֶּפֶשׁ אֲשֶׁר עָשׂוּ בְּחָרָן 12:5 the people he “created” in Charan by teaching them to have Emuna in Hashem; i.e., the true Ben-Torah wants others to share in his Torah (see Gr”a).
Practically no Shevet is known for Torah as much as Shevet Yehuda (Gemara), and we find: וְאֶת יְהוּדָה שָׁלַח לְהוֹרוֹת לְפָנָיו גשְׁנָה Vayigash 46:28 Yaakov Avinu sent Yehuda, the #1 Ben-Torah, to build a Yeshiva in Goshen. The Alter from Novardok Zatzal in his classic "לְזַכּוֹת אֶת הָרַבִּים" says that the main Zikkui HaRabbim is the responsibility of Bnei Torah. He brings a Chazal that the reason for the horrific story of Pilegesh B'givah was because the Sanhedrin of that Dor weren’t Moser Nefesh for Zikkui HaRabbim.
A true Ben-Torah is in general involved in caring for Klal Yisroel. During WWII, R’ Ahron Kotler and R' Avrohom Kalmanovich were seen on Shabbos being Moser Nefesh to save the Yidden in Europe. They gave away their time and Kochos and their Oneg Shabbos for the Klal. Perhaps this is why by far the two most astronomical Yeshivos in the world are Lakewood and Mir.
By the way, R' Avrohom Kalmanovich Zatzal was a big: עִיּוּן genius, and his father wanted him to just learn for himself, so he could Shteig to his full potential; but the Chofetz Chaim insisted that he get involved in Klal work. Imagine if he didn’t! And as we know, he was responsible for rescuing the Mir Yeshiva from the Nazis, Y'mach Sh'mam.
One of the reasons the Chofetz Chaim gave, was because if you work for the Klal, then you end up with much more Torah, since all the Torah that the Klal learns belongs to you! Hashem wouldn’t speak to Avraham Avinu while Lot was with him. (Rashi). Look how much Avraham Avinu gave away from himself to be M'karev others! (And in the end, we have Dovid HaMelech who was a descendant of Lot).
Also, the Netziv says that the reason why Sara was greater than Avraham Avinu in Nevua was because she was : מִתְבּוֹדֶדֶת alone at home, while he was outside being involved in Kiruv. Notice how R' Ahron Kotler Zatzal was always on the move to help Klal Yisroel and to build Lakewood.
And notice how R' Yisroel Salanter Zatzal took a trip all the way to Paris to be M'karev them. He also went to Amsterdam to be M'karev the people to keep Shabbos. At first, the Alter of Kelm Zatzal didn’t want to build Kelm, because he felt that he first needs to perfect himself in Torah and Avoda.
R' Yisroel Salanter Zatzal told him: “If you don’t build it now, it’ll never happen”. There is a major Yetzer Hara for a person to put things off in Zikkui HaRabbim. By the time he wakes up, he’s stuck in a lifetime stationary mode, and he’ll never achieve the greatness of his full potential. (Yet, for those who don’t have a Chinuch for the importance of Zikkui HaRabbim, this is fine). I heard this story from R’ Yehuda Jacobs Zatzal when he tried to persuade me to leave BMG for an out-of-town position. But those days, I didn’t have the Novardok Chinuch, and wouldn’t dream of leaving BMG...
