You made a good example. We often use the phrase "to hop on the bandwagon" Examples "I used to do everything that magazine suggested. When a new health recommendation came along I just hopped on the bandwagon." "You should go with the flow. Everybody is doing it so just hop on the bandwagon already!" Hope that helps.

A "bandwagon" (or "band-wagon" or "band wagon") literally means a parade wagon or "float" that carries a brass band. The phrase first became popular in respect to political candidates. The mental image is of a political candidate who looks like he must be successful because he has a big bandwagon in the parade. Thus "to jump on the bandwagon" means "to join the side that looks as if it is winning." A literal use of the word appears in a 1910 story by O. Henry: "The consul occupied a place somewhat near the tail of his political party's procession. The music of the band wagon sounded very faintly to him in the distance. The plums of office went to others." Apparently it was common for people to get rides on the bandwagon. Another old book mentions that "men, unlike quail, rather like to perch on a band wagon." A 1920 book gives an example of the meaning "to join sides with the apparent winner:" "He would have said that Sir Thomas, in regard to the policies or sentiments of the day, might always be found on the band-wagon—not because he always understood these policies and sentiments, but because the crowd clapped for 'em." By extension, the phrase has come to mean joining a movement, fad, or trend because it looks like it is becoming a success. In your example, the reason why the speaker is using chia seeds is mostly because so many other people are doing it. It must be good because everyone is doing it.