system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How is Obama able to show up to a random event like his nieces basketball game today?
gpt
It's much easier to show up at a random event than a planned event.  If the President is known to be appearing at such and such a place at such and such a time, then people who want to kill him have lots of opportunity to prepare.

If he just suddenly goes to an event with no prior notice where he was not expected to attend, its very unlikely that anyone there is interested in or capable of killing him.  The longer he's there, the higher the risk becomes as word spreads, so the Secret Service probably has him on a short timer and they have controlled access to the facility so that anyone going in is screened first for weapons.  At some point they know they have to get him out of there and back into the protective cocoon but for a while he can be a little bit "normal".