I am going to go against the grain a bit here @WhiteDust
I think there is a happy medium. Phoning you daily is a bit much. Wanting to join you on hols and with outings is a bit much.
They are not that old really in mid 70s though you say they have health issues. My parents made new friends in their 70s. My dad died a few weeks ago in his 90s. My mum has an active social life and she is 91. I live too far away for them to use me and my DCs as a means to alleviate boredom. I talk to my mum maybe 2-3 times a week.
What does come over is that you don't seem to love your parents. You appear resentful that they had lives that were busy when you were younger. There is no info about how they felt towards you- being busy as parents doesn't always mean you neglect your children.
Did you feel unloved?
I think your post is really sad. It seems that you want to pay them back for what they didn't give you when you were a child.
Did they help you at all? Did they do childcare? Were they hands on grandparents?
I think on the one hand you should show some compassion if you can. Most posts so far are about 'treat them as they treated you'. Hmm.
maybe they regret the past, maybe they realise time is running out.
Many of us do things for our parents we'd rather not. I drive for 5 hrs on my own to visit mum. I'm in my early 60s now, still work and also have DCs who are not married but live away so am pulled in all directions.
Mum did do a lot for me, so I feel it's only right I do what I can for her now.
I think you ought to encourage your parents to get new friends- they are not old! maybe include them with some things you do, but also explain that you need family time that doesn't include them. If you have caller display, let the phone ring and don't pick up every night. Don't return calls quickly...let them understand you are busy.
But don't do anything you will look back on and regret once they are dead. And also understand how you treat your parents is a role model for how your DCs may treat you . you never know how the future will pan out.