Because India does not need USA more than USA needs India. India hardly has any strategic weapons from USA and except for semiconductor, does not need USA at all. USA needs to sell weapons to India to reduce its trade deficit with India. If USA sanctions India, then USA will be harming its own trade balance.
Egypt does not have food. It has 10 crore population but produces food enough for only 3 crore. this means it has to import food for 70% of its population. Last time Muhammad Morsi had risen to Egypt's power but USA & GCC immediately cut foreign aid and investment to Egypt, causing severe foreign exchange reduction and difficulty in importing food. This food threat was the main reason why Morsi was overthrown and Sisi was placed as leader. So, Egypt will behave like a slave of GCC who control its finances and act according to the will of GCC's plan. Getting imported food is the priority of Egypt and everything else is secondary.
The extent of sanctions will depend on GCC countries. USA can't sanction the economy of any country without approval of GCC. GCC has to approve any dollar sanctions as according to petrodollar, dollar is also the currency of GCC countries and hence GCC has to approve of any sanctions. So, unless GCC agrees to put sanctions on Egyptian economy, USA can't sanction Egypt beyond sanctioning its military. For example, GCC did not approve of sanctions on Venezuela and hence Venezuela is not subject to economic sanctions like Iran. USA has only prohibited companies who are within USA to deal with Venezuela but there is no multilayered sanctions like Iran and non USA companies can still trade with Venezuela.
