Can someone who understands the strategy behind fundraising explain why they would want to raise at such a high valuation? To be clear, one point left out of th

Can someone who understands the strategy behind fundraising explain why they would want to raise at such a high valuation? To be clear, one point left out of the article is that the $3.5B - $4B valuation is a rumored valuation being "considered" by the startup (Their most recent round of funding valued them at $800MM). When I read about the "rumor" my immediate thought was: Snapchat leaked that to the press to gauge the response from potential investors / acquirers. The thing I don't understand is: what is their goal here? It seems like raising at a 3B+ valuation limits their options for an exit to either an IPO or an acquisition by one of maybe 3 companies. Raising at such a crazy valuation also seems extremely risky considering the volatility of apps in their space and the fact that they haven't even begun to explore monetization. What am I missing?