Yes, if you want to spend double the amount of money, loose all the character/memories and charm of your existing home, potentially not be allowed to construct what you want and contend with the following!
The inconvenience of moving house (twice if you get a long enough lease agreement, today’s markets see rentals sold for large capital growth leaving you stranded without accommodation or under new conditions), additional costs of this option include removalist fee’s twice, setting up services including phone, internet, electricity, water, foxtel, gas and so on plus breakages and items lost along the journey.
The cost of demolition and waste disposal.
rent, which are throw away costs.
Additional to that the cost of new floor coverings, curtains, landscaping, fencing, driveways, fittings and so on…
In most instances new homes may be subject to more restrictive floor space ratios and boundary limits enforced by your council and open to larger avenues of neighbour complaints and appeals against your intended works.