While things can start going wrong before 5 years another reason is the cost of routine maintenance due at 4 - 5 years and the choice to put the money into a newer car instead.
I paid for the work on my last car with a view of keeping until 10 years old although I changed just under 9 years, which as things turned out was well timed. My current car had an OTR price of £16,500 at January 2019. The production run was ending and relatively unpopular in the manufacturers range so probably deals to be had. Come December 2019 with 11,000 miles recorded I paid the franchised dealer £9,500. I sold my car to a local used trader rather than p/ex.
My usual annual mileage is 7,500 - 8,000 made up of 6,000 on commuting and local trips with the balance visiting friends & relatives, days out and annual holiday. However the current mileage of the car is only approaching 19,000 due to Covid resulting in much less leisure travel and furlough from work.
In two years time I have to make a choice
Option 1
Pay out £400+ for cambelt replacement, ~£150 for 2 year breakdown & recovery as much less than 2 x 1 year, £500 for 4 tyres, regular service £200 and MOT £50. Then keep the car 4 - 5 years.
Option 2
Put £1250+ towards another car.
I hope within 3 years to retire. Overall my annual mileage should fall but be mostly longer journeys for days out, short breaks and holidays. Given this I would choose a different car to be in for individual longer journeys. I will have some funds from my pension lump sum. However I certainly will not pay out ~£30,000 for a new EV. The price of a 1 - 2 year old EV and the realistic lifespan are unknowns.
At 10 years old / 60,000 miles my current car ought still to be very useable even if only worth £500. Hence an average capital cost of £1,000 per year.
If a 2 year old EV was £20,000 then effectively worthless at 10 years old because the batteries are life expired so unusable that is an average capital cost of £2,500 per year, which is way above my retirement budgeting. Even if maintenance is less that will only offset a small proportion of the much higher capital cost.
In terms of fuel the actual energy cost per mile for petrol / diesel and standard domestic rate electricity is similar. The total cost difference is because ~60% of the pump price for petrol & diesel is duty & VAT. As the number of EV's on the road increase the government can not afford the income loss so will recoup it in some way, most likely road pricing.
I do not know anyone with a pure EV and just one person with a hybrid which is a Toyota Yaris.