It’s hard work making it in the middle class

It’s hard work making it in the middle class

THE THUMPING BASS and intermittent shrieks of delight coursing through the neighborhood do not particularly bother Kristina Boldebuck. She’s charmed by the annual Billerica Lions Spring Carnival one street over, its scenes of classic Americana and the buzzy energy in the air. At night, Boldebuck can look out the window and see an illuminated Ferris wheel rising from behind her neighbors’ homes. The event is such a draw that her two kids came hom…