Not all SAHM's do the same thing. I know lots of SAHM's. Most of my friends are SAHM's.
I am a SAHM with a 3 year old. DD doesn't go to school yet, so my days are filled with DD related activities, squeezing in a bit of housework, seeing friends/my mum/my sister.
My sister is a SAHM. Her DC are aged between 7 and 17. She does school drop off, walks the dog, volunteers 3 days a week at the school, sees friends and family, housework, is on the PTA, is on the governing body of the school, helps out friends alot. She also works p/t evenings. (I could easily be happy living like this, busy, lots of friends but always there for the DC)
Friend A is a SAHM, spends her days doing the school run, an OU degree, sees friends, and housework. (I'd find this rather boring tbh, but as someone else has said..horses for courses)
Friend B is a SAHM. Her DD gets herself up and off to school (14 years old). She gets up at leisure, and spends her days reading books and watches startrek on tv or listens to meatloaf on the stereo. Yes, she really does watch the same program every day and hasn't listened to anything but meatloaf for 20 years.
Occasionally, she will see friends, probably about twice a week for an hour a time) Does minimum housework and cooks dinner for DD. (I'd go stark raving loony to live like this, but it's how she wants to live.)
Friend C is a SAHM to 2 DC. She drops the DC at school, then spends the day drinking tea with friends. After picking up her DC, she goes home and does her housework and dinner then.
When DD goes to school, I am looking forward to getting out of the house, either to go to college/uni or work. I am a people person and love to be out of the house. I also feel quite deflated if at the end of the day, I feel I have achieved nothing and every single day is exactly the same as the day before..the monotony would drive me insane.
There is nothing wrong with being a SAHM, but most of the SAHM's I know spend their lives watching tv, seeing friends, cooking and cleaning. I find that tedious and tiring. 