Not as simple as that. A pub landlord is very often a tenant/employee. The pub will be owned by a pubco (pub management company - they sprang up when breweries were made to divest themselves of pubs), which controls the purse-strings very tightly. There will be limited or no budget for entertainment and frills. He may well not even be on profit share, just a wage, for which he is expected to work 7 days a week, deal with all manner of awkward customers, employ staff, manage the accounts, etc, etc. He has no security, no property of his own and can easily be dispensed with if he displeases his employer. And if he loses his job, he loses his home - a similar situation to the one agricultural labourers in tied cottages were/are in. Not exactly a bed of roses.
As HH notes above, pubcos are often keen to sell their properties to developers - pubs are not the money spinners they once were - so are quite content for them to fail. The landlord has little or no control in that situation.
In the case of owned pubs and free houses, if a property developer offers a landlord/owner enough to retire on in comfort, enabling him to live a normal life and not work his @rse off every day, it's hardly surprising he will be tempted to accept. That has happened to several pubs round my way in North London in recent years.