Tesla (TSLA) bulls are preparing for the Mag 7 company's expected robotaxi launch later this month, though CFRA's Garrett Nelson urges caution. He says its Cybercab could be a letdown. One advantage Garrett believes Tesla has over competitors like Waymo: scalability. With sales plunging in China and Europe, Garrett warns that Tesla's finances in second quarter "may not be much better" than the first.