So you want everyone in the picture, including yourself.
You could set a timer, and take lovely pictures of yourself running back to the group, or suffer that embarrassing lag while everyone wonders if the camera + timer has worked.
Or you can use one of those remote control things... if you remembered
to bring it.
But better still ... you can just say 'CHEESE'.
I propose a trigger mode for cameras that is activated by a spoken keyword. Volume and voice recognition limits can be set so that it is not falsely triggered until the whole crowd or a nominated person says cheese (or whatever keyword you have picked).
While we are at it I also propose alternative variants using other indicators. Cameras already have smile recognition that detects the 'amount' of smile on each face (honest!). So we can alternatively trigger when a certain average or peak percentage smile (or other expression or pose) is present.
One supreme advantage of this technology is that a number of photographs can be taken without returning to the camera each time.