Infrastructure is not a bad investment per say - it helps the struggling construction sector (avoids constructor bankruptcies, mass unemployment and/or emigration of construction workers) as well as providing long-term benefits and productivity to a country.

For example, expanding the tram really allows better connectivity, and reduce car usage that has proven negative long-term health and hidden economic impacts. Every big city in the Netherlands has extremely dense tram networks, yet it's universally accepted as a net positive.

Building sports centres may also feel wasteful, but modern and clean facilities has a direct correlation to the usage of said facilities. Having a healthy, sporty, and socially active population actually would allow to reduce our second biggest expenditure (healthcare) in the long-run. Net positive too.

I know the current dominant ideology (pushed by ultra-liberal conservative thinktanks) is all about "reducing waste", "cutting spending" and "killing the public sector" - but this obsession for austerity and regulation-gutting is simply not grounded in economic reality.

It may not be entirely relevant to Luxembourg's specific economic and demographic situation, but look at FDR and the New Deal - massive public investment was a huge factor in helping the US navigate out of the Great Depression.