How can having too many followers be harmful in Bacon's opinion?

In his essay "Of Followers and Friends," Francis Bacon recommends that an individual should not accumulate too many followers because they may have ignoble intentions. He also suggests confining oneself to "ordinary" followers, rather than "costly," "factious," or "glorious" ones. The latter may base their attachment not in genuinely warm feelings but ulterior motives.
The least desirable followers are those who harbor "discontentment conceived against some other." That sort of motivation is likely to encourage the "ill intelligence" that well-known people display towards one another. By extension, these adherents' motives may in fact be to learn a person's secrets and communicate them to the one to whom they truly owe allegiance. In other words, they might be spies.
Instead, the author recommends, it is advisable to have and retain a select number of solid confidants: "some few friends." This practice will achieve a solid middle ground, because he also cautions against egotism that can result from over-reliance only on one's own judgment.