Lets imagine it really were a special kind if Starbucks card. It costs money to open, and to close. You can open at whatever capacity you like, and you can also use it to pay for things at other retail stores or to pay a bill. Sometimes the payment doesn't work, so its better to open more cards to more places.

You can only top up less than the original capacity. If you want more capacity you need to pay an opening fee again (possibly a closing fee too).

That's the thing when we use analogies. Its not always correct. Bitcoin and the lightning network are new and unique things.

On a more positive note I should say that maybe an analogy can help you get interested in learning more about bitcoin/lightning.