You cannot get an SPG credit card with 50,000 bonus points, as there is no SPG credit card available on the market right now.
Marriott acquired Starwood and the Starwood Preferred Guest program was merged with Marriot's loyalty program. So it's definitely worth taking a look at some of the best Marriot credit cards instead.
It's also worth checking out some of the best hotel credit cards if your travels take you to other hotel chains. And if you're a frequent traveler who doesn't want to be tied to a specific chain of hotels and resorts, it's worth taking a look at some of the best travel credit cards on the market. These could save you just as much at the same hotels, while giving you more redemption versatility for your travels.