Residents of the coastal south Dublin suburb of Blackrock, Bernie and John Gallagher, both 59, made their money from the interest they shared with the Beatty, Monahan, and Roche families in the €1.8bn PV Doyle hotel group, which was sold in 2007.
The group now owns the Doyle Collection of eight hotels here and in the UK that are valued at about €600m, and the Gallaghers own 25pc of the firm.
The couple's investment vehicle, Crownway, previously backed businesses in the security, energy, water and waste sectors. It also owns the Bord Gais Theatre and a number of other commercial properties here and in Poland. A 10pc stake in broadband firm enet is thought to have made them a profit of about €16m.