The fears for Britney Spears are piling up. Since the star split from ex-husband Sam Asghari last year, the singer has been exhibiting increasingly bizarre behavior and spending a fortune on anything she wants, and an insider claimed that if she doesn’t adapt to a stricter lifestyle, it may send her on a downward spiral. “She could run out of money if she keeps spending the way she’s spending,” the source told a magazine, pointing to her shopping sprees and endless vacations. “She’s earning a fraction of what she did in her peak earning years.” Though the mom-of-two, 42, vowed to never return …