Like a relationship, a home remodeling project is the most fun in its earliest stages. Remove and replace all contents of an average sized, three fixture bathroom including the tub/shower unit, toilet, sink, faucet, tub/shower valve, vanity and vanity top, installing new flooring, new exhaust fan, vanity light and mirror, bathroom accessories, little or no plumbing or electrical work beyond replacing the fixtures.
Since Contractors are in the business, they have the contacts to make such a strategic purchase (far below market value) and then the resources (contacts, parts sources, labor, skill, experience) to remodel it economically so that it looks great to a potential buyer.
A major upscale kitchen remodel that costs $100,000+ sees the addition of custom cabinets with enhanced storage features, stone countertops with a tile backsplash, upscale appliances, designer sink and faucet with water filtration system, lighting (including ambient lighting), and higher-end resilient flooring.
If you are going for a flat pack kitchen or an IKEA kitchen, then choosing the right combination of cabinets and having them delivered is all you need to take care of. Cabinetry is a major item that can hold up the whole project, so all timeframes need to be aligned around the delivery of this component.
The stress for the contractor is knowing, for example, that their client just committed to a $50K remodel, but after demo found water damage and mold and now has to inform the client that 1.) they can’t move forward with the remodel until the problem is fixed.