I've only ever had horrific experiences when doing them with other people. The other people freaked out and couldn't handle it and were never the same again afterwards.
Doing them by myself was a fantastic experience, I've done so multiple times. Absolutely one of my favorite experiences. Even better is the day after. One night I tripped on LSD and stayed up all night, and then when I got up in the morning these friends of mine were doing some mechanic work on a van, and I got down and helped them all afternoon on a whim. It was great. One of my favorite afternoons.
I do them frequently because I find it fun to bend and warp my perception of reality.
I find it less fun with people because it's distracting and usually everybody just ends up wanting to do their own thing.
Having experience both doing /psych/s alone and with people, they both have their pros and cons.
If you want to do them with other people, make sure these are people you're already comfortable with.
If you choose to do them alone, make sure you're in a good place to do them. Don't, like… take them in your room at 12 AM in your parents house while everyone is asleep. You'll most likely have a soykaf time.
I took shrooms with good friends recently, and I had an amazing experience.
I've also taken a vast amount of different psychs alone, and also had a good experience.
Can be fun, if you're with people you trust and get along with. Making collaborative art, talking about life, having sex, etc. are all really great, and IMO are often the most fulfilling uses of psychedelics. I don't trip with people if it's their first time any more though.
Doing them alone and staying alone can be great. Doing them with a group and staying with the group all night can also be great, with maybe short solo missions where you wander off for a few minutes. Starting off alone and then wandering into a group setting like a party midway is highly ill advised and must be avoided.