1. To protect herself from "A". We know "A" seems to have targeted Ali (as seen in Season 2, Episode 13: ”The First Secret”). Perhaps Ali needed all of that money to try and track "A" down. Or perhaps "A" was blackmailing her for cash.
2. To pay off someone else. "A" isn't the only one who potentially had it out for Ali. For example, there's the N.A.T. club — her other infamous enemy. We think Ian (Ryan Merriman) was crazy enough that he might have blackmailed or threatened Ali into giving him money.
3. To create the "A" team. Alternatively, there's the theory that Ali is really the one in charge of the "A" team, at least at this point. If so, maybe she needed the money to get her network of evil stalkers up and running. Secret lairs aren't free!
4. To fake her death. Related to several of these other theories, it's possible Ali faked her death, either to protect herself or to have more time to be evil (or both). If this was her plan, she might have needed the cash to start her new life — as someone who isn’t dead.
5. She didn't. One thing we know: Ali lies. It's possible she didn't need the money at all. Maybe she only blackmailed Byron to enjoy the smug satisfaction of having power over another person. And of course, some extra cash to fund her misdeeds wouldn’t hurt either.
Why do you think Ali needed the money? Let us know in the comments below.