I keep trying trains, here are some of my experiences. Caveat, I actually like/enjoy driving myself, but I want trains to be good for everyone including me.

Living in Wiltshire, within walking distance of a train station. Have friends in Kent, again walking distance of a train station. I was visiting those friends a few times a year, maybe even monthly at the time. I didn't have my own vehicle. Jumping on a train with a book, seemed like the good option. The cost was incredible, easily 4x the cost of fuel if I had a car/motorbike (as I later did). The trains were generally on-time, into London. Once I bought a vehicle (motorbike at the time) that became my default. The one time I wanted to leave the motorbike at home due to bad weather, the line was flooded between reading and Paddington and I had to take the bike in the rain anyway. It cost me less to pay the fuel, insurance and outright buy the motorbike in a year than I spent on the train.

Living in South Wales, travelling to leeds regularly (several times a month). Avoiding the road miles/fuel/carbon, trying to take the train. The journey is long, involved several changeovers. The worst changeover was at Cardiff, I had a 55 minute wait at the end of a 5+ hour journey before a final 20 minute train home. I did get a lot of reading done. I also got a lot of drinking done, that much time sat on a train and I'd have a few cans. Ironically google maps often told me to get off at a station before home, and walk the hour and twenty minutes from Cwmbran home, as it was quicker that taking the layover in Cardiff. Eventually started driving again.

South wales valleys, into cardiff. Rush hour traffic is horrendous. The drive to work at the weekend was around twenty minutes, during rush hour you'd add an hour to that at least. Started taking the train. Was regularly late to work as the rush hour trains would be at capacity and I wouldn't be able to get on, or they weren't running. I had a 35 minute wait at the station each evening after work, if I worked late I'd often get stuck waiting on the hourly train home. The train, while "in theory" quicker, was even slower than driving; it was less reliable and it worked out more expensive than the fuel.

The train should be a solid win. But time after time I've ended up buying a vehicle and going back to driving.

I commute to Manchester three times a week

Yeah because you're going to a major city. But if you're not going to a major city or you're going by a link then you start having problems.

If my train is 15 minutes late and I'm getting a connection in Manchester then it's a major issue, if you're getting off in Manchester it's a minor inconvenience.

It's sod's law that if your train is delayed then the connecting train will depart exactly on time. The other classic inevitable is that the size of the train is inversely proportionate to the expected passenger count.

I think it's very regional. I work in various places around Yorkshire, so I'm not always on the same route, but it's generally 10-20 trains a week (mixed with other weeks where I can walk or cycle from home). Of a 20 train week, I'd expect 1-2 delays or cancellations every day. Unless we're starting or finishing early/late, I'd expect a seat once, in one direction only.

These are mostly 2 carriage Sprinters with hundreds of people trying to get on them. Sometimes I work in other places, and you've got these enormous 10 carriage long things that run North/South, but only 50 people trying to get on, so you always get a seat on them.

I commute to Manchester

That's the only reason you're coping. Manchester is the greatest city in the World so it offsets the utter abortion that is train travel. Where are you coming from? North, East, South West? If it's some shitole town like New Mills I can imagine the train journey is a euphoric experience.

Edit to add: I go to London a couple of times a month. Not had a significant issue in years.

On second thoughts you may have brain damage. It's not normal to think train travel and London are acceptable to life. You should speak to your doctor and ask about traumatic brain injury or tumours. Could explain things.