But let's say you have a 50k 401k that you can borrow against in an emergency, and a 50k index fund - that's 75k in liquidity that you have available to you wit

But let's say you have a 50k 401k that you can borrow against in an emergency, and a 50k index fund - that's 75k in liquidity that you have available to you with a few days notice. 100k in the bank sitting there is getting you maybe 1% and the need for that money on an instant's notice seems...low.