Operator overload not defined error when type is accessed through const struct

[Tanaka]

I have a basic vector/point class where I've overloaded a bunch of arithmetical operators:

#pragma once

class point
{
public:

	point() 
	{

	}

	point(float p_x, float p_y, float p_z) : x(p_x), y(p_y), z(p_z) 
	{

	}

	point& operator+(point& right)
	{
		return point(x + right.x, y + right.y, z + right.z);
	}

	point& operator-(point& right)
	{
		return point(x - right.x, y - right.y, z - right.z);
	}

	point& operator*(point& right)
	{
		return point(x * right.x, y * right.y, z * right.z);
	}

	point& operator*(const float right)
	{
		return point(x * right, y * right, z * right);
	}

	point& operator*(const double right)
	{
		return point(x * right, y * right, z * right);
	}

	point& operator+=(point& right)
	{
		return point(x + right.x, y + right.y, z + right.z);
	}

	point& operator*=(const point& right)
	{
		return point(x * right.x, y * right.y, z * right.z);
	}

	point& operator*=(point right)
	{
		return point(x * right.x, y * right.y, z * right.z);
	}

	point& operator*=(const float& right)
	{
		return point(x * right, y * right, z * right);
	}

	point& operator*=(const double& right)
	{
		return point(x * right, y * right, z * right);
	}

	float x;
	float y;
	float z;
};

I can use it fine like

point p(50,50,50);
point q(50,50,50);
point t = p * q + q;

However when I put this point type into a struct and try to access the members after passing it through by const reference:

struct sextic {
	point a,b,c,d,e,f,g;
};

inline static sextic sexticDifference(const sextic &p_sextic1, const sextic &p_sextic2) 
{
	sextic result;
	result.a = p_sextic2.a - p_sextic1.a;
	result.b = p_sextic2.b - p_sextic1.b;
	result.c = p_sextic2.c - p_sextic1.c;
	result.d = p_sextic2.d - p_sextic1.d;
	result.e = p_sextic2.e - p_sextic1.e;
	result.f = p_sextic2.f - p_sextic1.f;
	result.g = p_sextic2.g - p_sextic1.g;

	return result;
}

This gives me an "operator not defined" error for compilation. How do I fix this, please?