Intending passengers, without a preoccupation with trains and the intricacies of their history and operation, want to get from A to B as quickly and comfortably as possible, but with a certainty of arrival at a guaranteed time. And to get back in similar fashion.
Part of that journey will start with a shorter journey to join a train, and a wait for it to arrive - often on a bleak platform with.poor weather protection. At the station nearest the ultimate destination a further short journey is required. Sometimes there may be a rail change or changes on further draughty platforms. An outward journey may fit needs well, but a return may be impractical or inconvenient thanks to timetabling and without any delays or cancellations.
It matters little whether any disruption is due to engineering work, a strike, trespassers near the line, broken down train, points failure, wires down, timetable chaos, crew sickness, delayed delivery of new trains or leaves on the line. The train was not there when needed and I missed my vital appointment. I decide to use an alternative method of transport next time.
In one case in my career I was due to chair a meeting near Euston Station, my train was delayed by an incident near Wakefield, my taxi from St Pancras got lost in traffic, and I arrived breathless to find my deputy had engineered a very successful coup prior to my delayed arrival. On that day my love for railways was very sorely tested.
There really is no practical alternative to rail for longer distance journeys, especially to London, but for many there is. Every delayed journey, whatever the reason, potentially loses many future journeys by train. Most rail passengers drive nice cars, just look at station car parks and the roadsides near all busy stations. A lot must have been used as rail substitutes during the recent Brighton line blockade when bus replacements were very lightly used.