> Engineering Manager positions often have more of an upside with bonuses / incentives than Engineers get

Not really.

Staff Eng and above will end up making similar to an EM including bonuses and has much more job mobility. You have to remember that most EM roles only open up once you hit Staff, so you are basically taking much more responsibility and longer hours for a marginal salary impact.

Engineering Manager jobs are hard to come by and your job security is actually less than an individual contributor, because even if an initiative was delivered late due to no fault of your own, if sales is braying for blood in order to protect themselves after failing to meet quota, it's the EM's head that is offered on a silver platter.