This is the best answer so far. Tell them, politely, to get lost and take it as a sign you are on the right track. It is time to damn the torpedoes, full-steam

This is the best answer so far. Tell them, politely, to get lost and take it as a sign you are on the right track. It is time to damn the torpedoes, full-steam ahead. They are either ahead of you or behind you and that is what they are trying to find out. If they are ahead and you have no unique tech then you are toast anyway. If they are behind they are weighing buying you to jump the line for Y dollars or investing X dollars to catch up. Why help them make that calculation? Make them sweat. If you have any confidence in what you are doing then stick with it and don't be distracted by BigCo.