It's not really the same as a loan - you don't pay it back with cash, it's paid for upfront with a chunk of equity (usually). And if the company fails, the investors take a bath & you aren't personally liable for it. Not fun but it happens all the time.

Why is it celebrated? Because A) the company suddenly has more capital in their bank account to grow the business and B) they have someone with connections and power who has a vested interest in the business succeeding, both of which improve the long-term likelihood of success/profit (in theory at least).

PS: many people do celebrate and post about it when they get a home loan, it's an exciting thing! Debt is a tool, it's not inherently shameful.