there are few backlogs, like availability of power and water this factors should be ensured before allowing high-rises in Delhi. As of now the Urban Development Ministry is currently in the process of reviewing the Master Plan of Delhi 2021 and is expected to finalise a number of amendments soon like allowing high-rises and increasing increasing the existing floor area ratio(FAR).
To construct high rise building there are few construction challenges, which need to be taken care of. Such as basic services like water supply, drainage and power distribution network should be reconstructed if vertical expansion in the city is allowed.
Sir i want to give answr to the second part of your question, that According to studies, buyers are willing to make investments in real estate, even though the supply of properties in Delhi is not rising. It is expected to boost the supply as well as the real estate revenue for the state.
One of the major reasons for acute shortfall of housing in Delhi is the lower floor area ratio(FAR) which does not allow high-rise apartments in Delhi. To wash off this reason, Union Urban Development Minister took an initiative to push Delhi for growing vertically.