Hypertensive Crisis: Given the patient's age, history of daily alcohol consumption, and presentation of tachycardia, hypertension, and lightheadedness, a hypertensive crisis is a plausible diagnosis. Alcohol can contribute to elevated blood pressure, and the sudden onset of symptoms could indicate a crisis.

Dehydration: Chronic alcohol use can lead to dehydration, which may cause tachycardia and lightheadedness. Hypertension could be a contributing factor or a result of dehydration.
Alcohol Withdrawal: Although the patient drinks daily, any recent reduction in alcohol intake could precipitate withdrawal symptoms, including tachycardia, hypertension, and lightheadedness.
Anxiety or Panic Disorder: These conditions can cause tachycardia, hypertension, and feelings of lightheadedness, especially in the context of alcohol use, which can exacerbate anxiety.

Myocardial Infarction (MI) or Acute Coronary Syndrome (ACS): Although less likely given the information, MI or ACS must be considered due to the patient's age and symptoms of tachycardia and hypertension, which could indicate cardiac ischemia.
Stroke or Transient Ischemic Attack (TIA): Lightheadedness, combined with hypertension, could be indicative of a cerebrovascular event, which is critical to diagnose promptly.
Pulmonary Embolism: This condition can cause tachycardia and lightheadedness and is a medical emergency that requires immediate diagnosis and treatment.

Pheochromocytoma: A rare tumor of the adrenal gland that can cause episodic hypertension, tachycardia, and lightheadedness due to excessive catecholamine release.
Thyroid Storm: A life-threatening condition that can cause tachycardia, hypertension, and altered mental status, including lightheadedness, in patients with untreated or undertreated hyperthyroidism.
Autonomic Dysfunction: Conditions affecting the autonomic nervous system, such as orthostatic hypotension or autonomic failure, could present with lightheadedness and tachycardia, especially in the context of positional changes.