An excellent question.
Why indeed are we giving away the sum equivalent to the entirety of the Marine Corps budget especially when they complain about recruiting shortfall and equipment issues?
Because Ukraine has been enmeshed in a hot war with Moscow for the last two years, and the Marine Corps isn't?
It’s a lot cheaper than either the increases Marines alone will need if Pooty “wins” or so much as breaks even (our enemies including him emboldened), or the even larger economic impacts that ripple down due to our enemies including him being emboldened.
But that’s just the short to medium term. Long term is much more violent / deadly.
That all said, the $60 billion should come out of domestic programs that do more harm than good. That’s where the real money is.