Not worth the money, imho.
Does Starbucks sell any hard goods? Preferably unbranded.
Victoria's Secret, at one point years ago, had the highest sales of classical music CDs. Impulse purchases.
Might be a way to burn off the card.
Buy the branded stuff and donate.
Or, show the card to a bunch of bums, and say "Follow me. I'm buying while the card lasts..."
Since CA has 35% of the homeless population, you will be able to find them all at the various Starbucks all over the state. Currently, those that live on the coast can stay outside to enjoy the nice weather, but those that have set up their homeless camps in the interior valleys will enjoy their time at the local Starbucks all summer long.
When winter comes those that have snow can enjoy their homeless populations with their morning coffee during the winter months.