Earlier quoted context omitted.
Avoid lifestyle creep! I have to say I'm bad at this myself: somehow it all adds up, while each individual expense doesn't look so bad.
There are also different types of creep, some that you can easily stop, and others that are more difficult. Specifically, everything that involves a medium to long-term obligation (such as a mortgage or vehicle loan) can cause problems if you cannot sustain it through cashflow interruptions or significant declines. Going out to expensive restaurants and Broadway shows definitely costs a lot of money, but you can imme…
That's why a budget is necessary, and you plan for emergency (of which a layoff is one). Saving up for an emergency fund means you don't spend on luxury until it is saved, which means no broadway or restaurants (unless you're super highly paid, in which case it'd be quite fast).