Time does most of the work. On the calculator's assumptions, the €444,000 above needs about €813 a month from age 35, in today's money. From 45 it needs about €1,371 a month, more than Revenue's age limit allows on €50,000 of pay.
Tax relief cuts the cost. Contributions get income tax relief at your marginal rate, so €100 into your pension costs €80 at 20% and €60 at 40%. On €50,000 in 2026, only the pay above €44,000 is taxed at 40%, so the €813 at 35 costs about €550 a month from take-home pay.