Nobody’s going to boycott a bank that gives them better deals than they can get anywhere else.
Banks are more highly leveraged and this vulnerable to a boycott than retail stores like Target or food processors like Kellogg. Especially when the bank is marketing to a niche market like the military, veterans, and their families. Their deposit base draws mostly from consumer deposits and their loans are mostly consumer based: auto loans and credit cards. If even 20 per cent of their depositors withdrew their funds, USAA would have a serious liquidity issue and would be forced to sell off their liquid assets and borrow at the Fed or money center banks.
Better deals? Vanguard/Fidelity/Schwab will give a higher return on investments. Most any insurance broker will give you a better price on auto/home/life.
USAA excels on customer service IMHO but they suck on deals.