Your files could be removed from Dropbox based on a third-party copyright claim, and repeated violations can result in account termination — even if the claims are disputed.
Dropbox's terms grant the company a broad license to your uploaded content to operate the service, and limit the company's liability for data loss or service interruptions. US users are required to resolve disputes through binding arbitration and waive the right to participate in class action lawsuits, significantly limiting legal recourse. You can opt out of arbitration by sending written notice to Dropbox within 30 days of first agreeing to these terms.