Parents might spend so much time cleaning up messes they get burned out and can't focus on work and miss out on a promotion. Ultimately, saving a few dollars by doing it all yourself can be much more costly in the long run.
A friend or family member needs money and asks you for a loan. You want to help, especially if it's someone you're close to. However, the time to decide how much you can float them is not in the middle of their crises.
You will be extremely nervous when the market crashes without one year of cash set aside. With one-year cash reserves, you have enough to stop distributions from your investments and wait out the market storms.