Rashi: He meant that Yisrael always follows an evil path, trying out Hashem. ¹

Ramban: He meant that they initially asked of Aharon was to provide a leader to replace Moshe, which Aharon did. And it was only afterwards that they decided to prostrate themselves before it and worship it.

Seforno: He meant that Yisrael were already accustomed to performing evil, when in Egypt they worshipped the Egyptian gods.

Targum Yonasan: He meant that they are really children of Tzadikim, and it is the Yeitzer ha'Ra that leads them astray.

Da'as Zekenim: He meant that, had Aharon not done [what they asked], they would have appointed a king over themselves, and the end would have been bitter.