How can I get my dad to make new friends and stop needing us to be his entertainment committee all the time?

My dad is 80 and can still live on his own presently, although we don't think that will last too much longer. Anyway my mom died three years ago and he has made no attempt to get out and make any new social connections. He wants myself and my three siblings to do everything with him. We live in a major retirement area and there are so many people he could be connecting with quite easily. But no, he wants us to shop, dine and travel with him. Sort of hard when we all work and are raising our own families. Plus he's a mean old man half the time and leaves us all exhausted trying to appease him. He says he can't stand old people lol so suggesting joining a club or travel group hasn't worked. As it is now we are all taking turns with him but we are all very tired of this. My sister recently told him she can't travel with him this fall and he is now being a huge ass to her. He thinks we all owe it to him to ensure he completes his "bucket list". We realize he's probably depressed and maybe even has early dementia but talking with him about it is also impossible because he just gets angry when we try to talk health issues with him. Yes, he is slightly controlling. Well, thanks for listening to me vent.