They have a massive incentive to force you to get one installed. By knowing the exact patterns of energy usage of their customers they can make more intelligent energy purchases thus pushing up profits, or enabling savings to customers (or a bit of both) depending on the operating model of the company,.
https://www.ofgem.gov.uk/publicatio...s-700000-after-missing-gas-smart-meter-target
Also, that isn't how the fine works. Energy suppliers with more than 250,000 customers must set annual targets for the proportion of their customers that will have smart meters by the end of each year. If the target is missed then enforcement action can be taken and they are fined. They are required by law to take all reasonable steps to roll out smart meters to all homes by the end of 2020.
The programme is expected to deliver 17.1 bn of economic benefits against costs of 10.9bn:-
They don't expect everyone to agree to have a meter initially, but you can bet if there is money to be made / losses to be avoided, that they will do all that they can to persuade you to change meter.