Lindsay Lohan's Mgmt Team -- She's Hell-Bent On Financial Ruin

Lindsay Lohan is careening toward financial ruin ... by making stupid business decisions and recklessly stashing her money in unsafe places -- this according to her management team.

TMZ has seen text messages between Michael Lohan and Lindsay's lawyer Dave Feldman, discussing Lindsay's recent promotion deal with an energy drink named Mr. Pink.

As we reported, Lindsay flew out to L.A. earlier this month in order to attend a launch event for the beverage -- just hours after her blowout fight with her mother Dina in NYC.

In the text messages, Michael claims Lindsay was paid $150,000 for the event IN CASH ... which Lindsay then gave to her brother Michael Jr. to hold in his bank account for safe keeping. Michael expressed fear that Dina had access to Michael Jr.'s account and would raid it for herself.

Dave expresses outrage in response, claiming Lindsay should have looped him and her business manager in to the Mr. Pink transaction in order to provide her more financial protection ... but she never did.

In the messages, Dave says Lindsay was even more stupid for not including her management team on the Mr. Pink deal because -- as Dave says -- they could have gotten her even more money for the job ... but again, she didn't.

As we reported, Lindsay's dad is terrified she has fallen back off the wagon and needs a conservatorship because she can't handle her affairs -- and based on these texts, he might have a point.